Show off going round in uniform (4)
I believe the answer is:
garb
'uniform' is the definition.
(I've seen this in another clue)
'show off going round' is the wordplay.
'show off' becomes 'brag' (both can mean to boast about something).
'going round' says the letters should be written backwards.
'brag' in reverse letter order is 'GARB'.
'in' is the link.
(Other definitions for garb that I've seen before include "Clothe" , "something to wear" , "Attire, clothing" , "Outfit" , "gear discovered" .)