Small tee between posts damaged part of golf club? (5,4)
I believe the answer is:
sweet spot
'part of golf club?' is the definition.
(best area of a club to hit a ball with)
'small tee between posts damaged' is the wordplay.
'small' becomes 'wee' (Scottish term for small).
'tee' becomes 't'.
'between' is an insertion indicator.
'damaged' indicates anagramming the letters.
'wee'+'t'='weet'
'posts' with letters rearranged gives 'sspot'.
'weet' inserted inside 'sspot' is 'SWEET SPOT'.
(Other definitions for sweet spot that I've seen before include "Area on club, racket or bat that makes best contact with the ball" , "Best area of a tennis or squash racket" , "Most effective section of racket" , "best part of club" , "providing an optimum combination of qualities" .)