Limit holding worker back from sleep (6)
I believe the answer is:
catnap
'sleep' is the definition.
(catnapping is a kind of sleeping)
'limit holding worker back' is the wordplay.
'limit' becomes 'cap' (capping is a kind of limiting).
'holding' is an insertion indicator.
'worker' becomes 'ant' (worker is a type of ant).
'back' says the letters should be written backwards.
'ant' back-to-front is 'tna'.
'cap' going around 'tna' is 'CATNAP'.
'from' acts as a link.
(Other definitions for catnap that I've seen before include "For a rest" , "little snooze" , "Forty winks (for moggy?)" , "(Tom's) snooze?" , "go out briefly" .)