Joined dance, on retirement, in church (7)
I believe the answer is:
cognate
'joined' is the definition.
'dance on retirement in church' is the wordplay.
'dance' becomes 'tango' (tangoing is a kind of dancing**).
'on retirement' says the letters should be written in reverse.
'in' is an insertion indicator.
'church' becomes 'ce' (abbreviation for Church of England).
'tango' reversed gives 'ognat'.
'ognat' going inside 'ce' is 'COGNATE'.
(Other definitions for cognate that I've seen before include "Of the same family" , "Related, connected" , "with similar origins" , "Related, having same source" , "Affiliated" .)