Avail oneself of some sheep we hear (3)
I believe the answer is:
use
'avail oneself of' is the definition.
(I've seen this in another clue)
'some sheep we hear' is the wordplay.
'some sheep' becomes 'ewes' (a ewe is a female sheep).
'we hear' indicates a 'sounds like' (homophone) clue.
'ewes' sounds like 'USE'.
(Other definitions for use that I've seen before include "Avail oneself of" , "Manipulate" , "Operate" , "Employ - advantage" , "Put into service, do something with" .)