Failing to notice girl during golf (7)
I believe the answer is:
missing
'failing' is the definition.
(missing is a kind of failing)
'girl during golf' is the wordplay.
'girl' becomes 'miss' (term of address for an unmarried woman).
'during' becomes 'in' (e.g. during February means in February).
'golf' becomes 'g' (phonetic alphabet: alpha, bravo, charlie etc.).
'miss'+'in'+'g'='MISSING'
'to notice' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for missing that I've seen before include "Not to be found" , "Absent with location unknown" , "Lost without" .)