Golfer putting about on one green (7)
I believe the answer is:
trevino
'golfer' is the definition.
(I have seen 'Old golfer' mean 'trevino' so perhaps 'golfer' could also mean 'trevino')
'about on one green' is the wordplay.
'about' is a reversal indicator.
'one' becomes 'I' (Roman numeral).
'green' becomes 'vert' (heraldic term for green).
'on'+'i'+'vert'='onivert'
'onivert' backwards is 'TREVINO'.
'putting' acts as a link.
(Other definitions for trevino that I've seen before include "Lee -, US golfer" , "Old golfer" .)