Boy good as dance partner? (4)
I believe the answer is:
song
'dance partner?' is the definition.
(I've seen this in another clue)
'boy good' is the wordplay.
'boy' becomes 'son' (synonyms).
'good' becomes 'g' (abbreviation).
'son'+'g'='SONG'
'as' acts as a link.
(Other definitions for song that I've seen before include "Vocal composition" , "Piece of vocal music" , "Carol, for example" , "Melody (which is cheap to go for)" , "Musical composition with words" .)