Muscular aficionado (4)
I believe the answer is:
buff
This clue is a double definition.
'muscular' is the first definition.
(I've seen this in another clue)
'aficionado' is the second definition.
(both can mean a fan or enthusiast)
(Other definitions for buff that I've seen before include "Dull yellow" , "An informal enthusiast as for rugby" , "Yellowish brown" , "Polish; yellowish-beige" , "Bare skin - enthusiast" .)