Guy in a sty (4)
I believe the answer is:
boar
'guy in a sty' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for boar that I've seen before include "Male swine" , "Sow's mate" , "A wild male pig" , "The head for drink Falstaff had" , "Resting place for birds or bats" .)