Wanted to see the gentleman in action (7)
I believe the answer is:
desired
'wanted' is the definition.
(similar in meaning)
'the gentleman in action' is the wordplay.
'the gentleman' becomes 'sir' (a man may be addressed as sir).
'in' means one lot of letters goes inside another.
'action' becomes 'deed' (deed is a kind of action).
'sir' placed within 'deed' is 'DESIRED'.
'to see' acts as a link.
(Other definitions for desired that I've seen before include "much wished for" , "Sought after" , "Lusted-after" , "Wanted greatly" , "requested" .)