Scottish headwear (3)
I believe the answer is:
tam
'scottish headwear' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for tam that I've seen before include "Scotsman's cap" , "Index rating for TV watching" , "Ratings compiled on TV listener numbers" , "'Woollen cap of Scottish origin, in short (3)'" , "Turn over the mat for a cap" .)