(Very) short skirt (4)
I believe the answer is:
mini
'very short skirt' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for mini that I've seen before include "Once fashionable skirt" , "type of garment" , "Iconic economy car (introduced in 1959)" , "Car designed by Issigonis" , "Small (of car, skirt, disk,bar or series)" .)