Dance, heartlessly frivolous pleasure (7)
I believe the answer is:
delight
'pleasure' is the definition.
(I know that pleasure can be written as delight)
'dance heartlessly frivolous' is the wordplay.
'heartlessly' suggests removing the centre.
'frivolous' becomes 'light' (light can mean trivial or unimportant).
'dance' with its centre removed is 'de'.
'de'+'light'='DELIGHT'
(Other definitions for delight that I've seen before include "Joy" , "Greatly please" , "Rejoice" , "Glee; its spirit rare, Shelley" , "Lighted to give real pleasure" .)