Core material in support of golfer recalled in well-chosen words (7)
I believe the answer is:
epithet
'well-chosen words' is the definition.
(an epithet is an apt name for someone)
'core material in support of golfer recalled' is the wordplay.
'core material' becomes 'pith' (pith can mean something's core or essence).
'in' is an insertion indicator.
'support of golfer' becomes 'tee' (a tee supports a golf ball).
'recalled' shows that the letters should be reversed in order.
'tee' reversed gives 'eet'.
'pith' inserted into 'eet' is 'EPITHET'.
'in' acts as a link.
(Other definitions for epithet that I've seen before include "Word describing" , "qualifier" , "Descriptive work or phrase" , "The 23: an -- for Richard I" , "Descriptive term or short phrase" .)