Inane dancing in musical (5)
I believe the answer is:
annie
'musical' is the definition.
(I've seen this before)
'inane dancing' is the wordplay.
'dancing' indicates an anagram.
'inane' is an anagram of 'ANNIE'.
'in' is the link.
(Other definitions for annie that I've seen before include "musical movie" , "Girl with gun in musical" , "Little orphan girl" , "- Get your Gun, musical" , "- Hall, Woody Allen film" .)