CO allegedly held back with hesitation (6)
I believe the answer is:
doctor
'hesitation' is the definition.
The definition and answer can be both acts as well as being singular nouns.
Perhaps there's a link between them I don't understand?
I can't explain the remainder of the clue.
(Other definitions for doctor that I've seen before include "Onshore breeze" , "Ship's cook" , "Eg, surgeon" , "Medical specialist" , "GP" .)