Tee shirt? (10)
I believe the answer is:
turtleneck
'tee shirt?' is the definition.
(turtleneck is a kind of tee shirt)
This is all the clue.
(Other definitions for turtleneck that I've seen before include "Type of jumper (between crew- and polo-)" , "clothing" , "Type of sweater" , "Sweater similar to polo" , "High-topped jersey" .)