Respond with gold generator (7)
I believe the answer is:
reactor
'generator' is the definition.
(thesaurus)
'respond with gold' is the wordplay.
'respond' becomes 're-act' (to react to something is to respond to it).
'with' is a charade indicator (letters next to each other).
'gold' becomes 'or' ('or' is the heraldic name for gold).
'react'+'or'='REACTOR'
(Other definitions for reactor that I've seen before include "Nuclear power plant" , "Nuclear installation" , "power supplier" , "Creator (anag.)" , "Nuclear power generator" .)