Peg's style of shirt? (3)
I believe the answer is:
tee
This clue is a double definition.
'peg's' is the first definition.
(tee is a kind of peg)
'style of shirt?' is the second definition.
(I've seen this in another clue)
(Other definitions for tee that I've seen before include "Golfer's peg" , "supporter on course" , "Golfer's support" , "Starting peg" , "Golf ball support" .)