Drink is golfer’s support, they say (3)
I believe the answer is:
tea
'drink' is the definition.
(tea is a kind of drink)
'golfer's support they say' is the wordplay.
'golfer's support' becomes 'tee' (I've seen this before).
'they say' shows a homophone (sound like).
'tee' is a homophone of 'TEA'.
'is' acts as a link.
(Other definitions for tea that I've seen before include "Strangely, ate this drink" , "Common drink" , "Meal/drink" , "leaves much to be desired?" , "Beverage from leaves" .)