Frank is capable, and has done (6)
I believe the answer is:
candid
'frank' is the definition.
('candid' can be a synonym of 'frank')
I can't explain the rest of the clue.
Can you help me to learn more?
(Other definitions for candid that I've seen before include "Frank, honest" , "Blunt; frank" , "Frank and outspoken" , "Forthrightly sincere" , "Free and frank" .)