One who'd change for dance (7)
I believe the answer is:
hoedown
'for dance' is the definition.
(I've seen this before)
'one who'd change' is the wordplay.
'change' indicates anagramming the letters.
'one'+'whod'='onewhod'
'onewhod' is an anagram of 'HOEDOWN'.
(Other definitions for hoedown that I've seen before include "Woodhen (anag.)" , "Square 20" , "Hillbilly dance" , "US folk dance gathering" , "Lively folk dance (US)" .)