Uncastrated male pig (4)
I believe the answer is:
boar
'uncastrated male pig' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for boar that I've seen before include "Sow's mate" , "Uncastrated male hog" , "The head for drink Falstaff had" , "Wild pig sounds tedious" , "Wild animal, sounds like drill" .)