Rear wheel movement and slight clicking noise

[Ajax Bay]

You don’t want them too tight, I’m talking about a very slight bit of movement.

"You don’t want them too tight. I’m talking about [not even the] slight[est] bit of movement" once the QR levers are properly tight (mark in hand).
If they're too tight then the wheel won't spin smoothly. If they're too loose then the QR lever won't compress the bearing enough and you'll get the OP's symptom. Mummy bear challenge.

 

[Globalti]

If there's play at the rim the wheel needs new bearings, which a bike mechanic can fit in a few minutes. If you hold the axle ends and spin the wheel, can you feel roughness? That's the bearings.

 

[biggs682]

As for the rear triangle, the hangers are all in good shape and the frame is carbon with no rust or marks on it.

But has it been in the rain as we all know Carbon melts in rain

 

[recumbentpanda]

"You don’t want them too tight. I’m talking about [not even the] slight[est] bit of movement" once the QR levers are properly tight (mark in hand).
If they're too tight then the wheel won't spin smoothly. If they're too loose then the QR lever won't compress the bearing enough and you'll get the OP's symptom. Mummy bear challenge.

Erm, correct me if I am being dense here, but surely qr levers, or for that matter solid axle nuts should have no effect whatever on the bearings. If they are somehow compressing them, then the design of bicycle axles is really not what I thought it was . . . Puzzled.

 

[Ajax Bay]

surely QR levers, or for that matter solid axle nuts should have no effect whatever on the bearings.

Have a read of this.
"Quick-release hubs are trickier to adjust, because the quick-release mechanism compresses the axle slightly when it is tightened. If you adjust the cones so that they feel just right off the bike, they will bind up when you tighten the quick release. You must set the cones so that there is a little bit of play when the hub is off the bike, or when the wheel is installed with the quick release just barely tightened."

 

[Apollonius]

Fulcrum Racing 5s have cartridge bearings, or at least, the more recent ones do. Some of them have a little band adjuster that allows you to put a bit of pressure on the bearing to take up wear. I think that is on the more recent ones (2015 ones have this). If you have the adjustable type, take the wheel out, and you will see a little band round the hub axle with a tiny allen key fitting in it. Loosen the band with the allen key, rotate it round the hub a little and it will tighten. In my experience, this is not a very long-lasting fix. If the bearing is worn, then you might as well get it - or them, as there are two in a hub - replaced. This is not expensive. Even the best bearings only cost a few ponds, and these are a common size. If you are used to doing your own repairs, this isn't too difficult, but you will need a bearing press to make sure the new bearings go in straight.

At this point, I will confess to a cock-up the last time I did this. I have Fulcrum 5s on a few of my bikes, and had (I think) 30mm bearings "in stock". Merrily knocked out the old bearings and then found I was getting nowhere with the press-fit. Micrometer soon told me the ones I had taken out were 28mm. Off to the LBS! Probably the best advice, really.

 

[DSK]

But has it been in the rain as we all know Carbon melts in rain

When I said no rust, I meant no rusty nuts/bolts/cables to indicate neglect or use in wet weather.