Mexican hat (8)
I believe the answer is:
sombrero
'mexican hat' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for sombrero that I've seen before include "Mexican's hat" , "Large Mexican sun-hat" , "a Mexican's overheads" , "Broad-brimmed Mexican hat" , "Wide-brimmed hat of Mexico" .)