Liberal Spanish gent added to working capital (6)
I believe the answer is:
london
'capital' is the definition.
(capital of the United Kingdom)
'liberal spanish gent added to working' is the wordplay.
'liberal' becomes 'l' (abbreviation).
'spanish gent' becomes 'don' (formal term of address for a man in Spanish).
'added to' is a charade indicator (letters next to each other).
'working' becomes 'on' (on can mean working or activated).
'don' after 'on' is 'ondon'.
'l'+'ondon'='LONDON'
(Other definitions for london that I've seen before include "UK's capital" , "City of the Cockneys" , "British capital" , "Home of Cockney" , "- Clay; - pride; - plane" .)