Nail polish back in style, man explains (6)
I believe the answer is:
enamel
'nail polish' is the definition.
(I've seen this before)
'back in style man explains' is the wordplay.
'back' says the letters should be written backwards.
'in' indicates the answer is hidden within the clue.
'lemane' can be found hidden inside 'style man explains'.
'lemane' in reverse letter order is 'ENAMEL'.
(Other definitions for enamel that I've seen before include "found on crowns" , "Hard gloss paint" , "protection for canines?" , "Hard shiny coating on surface" , "protective coat" .)