Rob Morse of his strange hat (8)
I believe the answer is:
sombrero
'rob morse of his strange hat' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for sombrero that I've seen before include "Straw hat with very wide brim from Mexico" , "It may be felt" , "Rob Morse of his strange hat" , "headgear from Mexico" , "Large Mexican sun-hat" .)