City house for nymph (4)
I believe the answer is:
echo
'for nymph' is the definition.
(figure of Greek myth)
'city house' is the wordplay.
'city' becomes 'EC' (the City of London postcode).
'house' becomes 'ho' (abbreviation for house).
'ec'+'ho'='ECHO'
(Other definitions for echo that I've seen before include "repercussion" , "call back" , "copy" , "Nymph; E (radio comms.)" , "from Brussels?" .)