Those counted, on the quiet, when you want a bit of sleep (5)
I believe the answer is:
sheep
'want a bit of sleep' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'those counted on the quiet when' is the wordplay.
I cannot really understand how this works, but
'quiet' could be 'sh' (both can be said to tell someone to be quiet) and 'sh' is found in the answer.
This may be the basis of the clue (or it may be nonsense).
'you' acts as a link.
Can you help me to learn more?
(Other definitions for sheep that I've seen before include "- may safely graze (Bach)" , "feature of 21/23 [NATIVITY SCENE]" , "Ewe" , "One lacking initiative (but better than a goat?)" , "Eg, a merino" .)