Granny prepared for return in French city (6)
I believe the answer is:
nantes
'french city' is the definition.
(Nantes is a city in France)
'granny prepared for return' is the wordplay.
'granny' becomes 'nan'.
'prepared' becomes 'set' (set up or ready).
'for return' is a reversal indicator.
'set' reversed gives 'tes'.
'nan'+'tes'='NANTES'
'in' acts as a link.
(Other definitions for nantes that I've seen before include "Port city on the Loire estuary" , "French Atlantic port" , "port abroad" , "Site of historic drownings" , "Loire city; its tolerant Edict" .)