Fan removes uniform for closest mate (4)
I believe the answer is:
buff
'fan' is the definition.
(I know that fan can be written as buff)
I can't explain the rest of the clue.
(Other definitions for buff that I've seen before include "nude?" , "Yellowish colour - polish - expert" , "Polish; expert, devotee" , "Polish; yellowish-beige" , "Dull brownish-yellow - expert" .)