Perhaps champion golfer is one of the top ones in the pack (3,2,5)
I believe the answer is:
ace of clubs
'perhaps champion golfer' is the definition.
'ace of clubs' can be an answer for 'golfer' (I have seen 'Top golfer' mean 'ace of clubs' so perhaps 'golfer' could also mean 'ace of clubs'). I'm not sure about the 'perhaps champion' bit.
'one of the top ones in the pack' is the wordplay.
I cannot really see how this works, but
'one' could be 'club' (I've seen this before) and 'club' is found within the answer.
'of' could be 'o' and 'o' is found within the answer.
'top' could be 'ace' and 'ace' is located in the answer.
This explanation may well be incorrect...
'is' acts as a link.
Can you help me to learn more?
(Other definitions for ace of clubs that I've seen before include "card?" , "brilliant Batman!" , "finest social venue" , "Top golfer" , "one in a black suit" .)