Old man's second exam result (4)
I believe the answer is:
pass
'result' is the definition.
(I know that result is a more specific form of the action pass)
'old man's second' is the wordplay.
'old man's' becomes 'pa's' (both can mean someone's father).
'second' becomes 's' (common abbreviation).
'pas'+'s'='PASS'
'exam' is the link.
This may not be right. It may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for pass that I've seen before include "Amatory advance" , "change" , "Go by; mountain route" , "Overtake; permit" , "Go by; succeed in (an exam)" .)