Counterpart of Dancing Queen? It keeps John twirling (10)
I believe the answer is:
equivalent
'counterpart' is the definition.
(thesaurus)
'dancing queen? it keeps john twirling' is the wordplay.
'dancing' is an anagram indicator.
'keeps' is an insertion indicator.
'john' becomes 'lav' (both can mean a toilet).
'twirling' is a reversal indicator.
'lav' written backwards gives 'val'.
'queen'+'it'='queenit'
'queenit' with letters rearranged gives 'equient'.
'equient' placed around 'val' is 'EQUIVALENT'.
'of' acts as a link.
(Other definitions for equivalent that I've seen before include "Equal" , "Interchangeable" , "corresponding" .)