Age letter repulsed by golf (3,2)
I believe the answer is:
get on
'age' is the definition.
(synonyms)
'letter repulsed by golf' is the wordplay.
'letter' becomes 'note' (note is a kind of letter).
'repulsed' says the letters should be written in reverse.
'by' is a charade indicator (letters next to each other).
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'note' backwards is 'eton'.
'eton' put after 'g' is 'GET ON'.
(Other definitions for get on that I've seen before include "Make progress; be friends" , "Hit it off" , "Age; prosper" , "Proceed; prosper" , "Make progress or climb aboard" .)