What may be worn — more short robes, properly tailored (8)
I believe the answer is:
sombrero
'what may be worn' is the definition.
(I know this)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for sombrero that I've seen before include "Broad-brimmed Mexican hat" , "Rob Morse of his strange hat" , "Wide-brimmed hat of Mexico" , "headgear from Mexico" , "a Mexican's overheads" .)