Hunt illegally (5)
I believe the answer is:
poach
'hunt illegally' is the definition.
(synonyms)
This is the entire clue.
(Other definitions for poach that I've seen before include "Cook in a simmering liquid" , "Cook in hot water" , "Steal (game) - cook (eggs)" , "Cook; hunt illegally" , "Take game illegally from land or water" .)