Warm male with a sheep (4,2)
I believe the answer is:
heat up
'warm' is the definition.
(I've seen this in another clue)
'male with a sheep' is the wordplay.
'male' becomes 'he' (he refers to a man).
'with' means one lot of letters go next to another.
'sheep' becomes 'tup' (tup is a kind of sheep).
'he'+'a'+'tup'='HEAT UP'
(Other definitions for heat up that I've seen before include "Make more intense" , "Warm through" .)