Swine, one who’s uninteresting to listen to (4)
I believe the answer is:
boar
'swine' is the definition.
(male pig)
'one who's uninteresting to listen to' is the wordplay.
'one who's uninteresting' becomes 'bore' (boring person).
'to listen to' shows a homophone (sound like).
'bore' sounds like 'BOAR'.
(Other definitions for boar that I've seen before include "The head for drink Falstaff had" , "Wild animal, sounds like drill" , "A male pig, sounds tedious" , "Wild swine" , "Uncastrated male hog" .)