Group granny knocked over in French city (6)
I believe the answer is:
nantes
'french city' is the definition.
(Nantes is a city in France)
'group granny knocked over' is the wordplay.
'group' becomes 'set' (both can mean a collection).
'granny' becomes 'nan'.
'knocked over' is a reversal indicator.
'set'+'nan'='setnan'
'setnan' in reverse letter order is 'NANTES'.
'in' is the link.
(Other definitions for nantes that I've seen before include "French Atlantic port" , "French football club" , "Western French port" , "Ann set out for the French town" , "French FC" .)