Grandma put up in French city (6)
I believe the answer is:
nantes
'french city' is the definition.
(I've seen this before)
'grandma put up' is the wordplay.
'grandma' becomes 'nan' (I've seen this before).
'put' becomes 'set' (setting is a kind of putting).
'up' says the letters should be written in reverse (in down clue: letters go upwards).
'set' in reverse letter order is 'tes'.
'nan'+'tes'='NANTES'
'in' is the link.
(Other definitions for nantes that I've seen before include "A major French port" , "City in Brittany" , "Loire port; an old Edict" , "French city noted for edict" , "in Pays de la Loire?" .)