A person of intelligence no doubt (6,5)
I believe the answer is:
secret agent
'a person' is the definition.
(secret agent is a kind of person)
'intelligence no doubt' is the wordplay.
I cannot quite see how this works, but
'intelligence' could be 'gen' and 'gen' is found in the answer.
This explanation may well be incorrect...
'of' is the link.
Can you help me to learn more?
(Other definitions for secret agent that I've seen before include "Conrad character" , "007 - centre stage (anag)" , "Spy" .)