Clothes which can be changed (4)
I believe the answer is:
gear
I believe this clue is a double definition.
'clothes' is the first definition.
(I've seen this before)
'which can be changed' is the second definition.
(as in changing gear on a vehicle)
(Other definitions for gear that I've seen before include "illegal drugs" , "often changed when driving" , "Toothed wheel used when changing speed" , "Toothed wheel mechanism" , "Clothes (first or second, perhaps?)" .)