He may follow an ace with clubs of course (6)
I believe the answer is:
caddie
'he may follow an ace with clubs of course' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'he may follow an ace with clubs' is the wordplay.
I cannot really understand how this works, but
'he' could be 'addie' and 'addie' is located in the answer.
'clubs' could be 'c' (abbreviation used in card games such as bridge) and 'c' is found within the answer.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for caddie that I've seen before include "Golfer's aide" , "Wages advice note" , "A golfer's assistant (6)" , "Padraig Harrington's brother-in-law Ronan Flood is also his . . . . . ." , "club assistant" .)