Spy is a refined chap (5)
I believe the answer is:
agent
'spy' is the definition.
(secret agent)
'a refined chap' is the wordplay.
'refined chap' becomes 'gent' (I've seen this in another clue).
'a'+'gent'='AGENT'
'is' acts as a link.
(Other definitions for agent that I've seen before include "Catalyst" , "factor in Scotland" , "Delegate" , "Bond, e.g." , "Substance that exerts some force or effect" .)