Uncovered belly-button on return of American Smooth (5)
I believe the answer is:
suave
'smooth' is the definition.
(I know that smooth can be written as suave)
'uncovered belly-button on return of american' is the wordplay.
'uncovered' indicates the central letters.
'belly-button' becomes 'navel' (I've seen this before).
'on' is a charade indicator (letters next to each other).
'return' shows that the letters should be reversed in order.
'of american' becomes 'US' (United States).
The middle of 'navel' is 'ave'.
'us' written backwards gives 'su'.
'ave' put after 'su' is 'SUAVE'.
(Other definitions for suave that I've seen before include "Superficially polite" , "Smooth-tongued" , "Urbane and sophisticated" , "Charming, confident" , "Smooth-mannered and sophisticated" .)