Girl in Golf absent (7)
I believe the answer is:
missing
'absent' is the definition.
(I know that absent can be written as missing)
'girl in golf' is the wordplay.
'girl' becomes 'miss' (term of address for an unmarried woman).
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'miss'+'in'+'g'='MISSING'
(Other definitions for missing that I've seen before include "Absent with location unknown" , "Not to be found" , "Lost without" .)