Make fun of nudes dancing on piano (4,2)
I believe the answer is:
send up
'make fun of' is the definition.
(I've seen this before)
'nudes dancing on piano' is the wordplay.
'dancing' indicates anagramming the letters.
'on' is a charade indicator (letters next to each other).
'piano' becomes 'p' (musical abbreviation).
'nudes' is an anagram of 'sendu'.
'sendu'+'p'='SEND-UP'
(Other definitions for send up that I've seen before include "Make fun of or despatch aloft" , "Mock?" , "Satirise" , "Mockery" , "Parody (of something)" .)