Beat young sheep endlessly (3)
I believe the answer is:
lam
'beat' is the definition.
(I've seen this in other clues)
'young sheep endlessly' is the wordplay.
'young sheep' becomes 'lamb' (I've seen this before).
'endlessly' means to remove the last letter.
'lamb' with its last letter removed is 'LAM'.
(Other definitions for lam that I've seen before include "Thump; leg it" , "Hit hard, strike" , "US criminals commonly escape?" , "On this, you're fleeing, from the police" , "pelt" .)