Wardrobe fitting containing suit (5)
I believe the answer is:
befit
'suit' is the definition.
(I know that suit can be written as befit)
'wardrobe fitting containing' is the wordplay.
'containing' indicates a hidden word.
'BEFIT' is hidden within 'wardrobe fitting'.
(Other definitions for befit that I've seen before include "Become, suit" , "Be right and suitable for" , "Be appropriate for" .)