Forgive the average and return the sign of assent (6)
I believe the answer is:
pardon
'forgive' is the definition.
(I know that pardon is a kind of forgive)
'average and return the sign of assent' is the wordplay.
'average' becomes 'par' (average score in golf).
'and' is a charade indicator (letters next to each other).
'return' is a reversal indicator.
'the sign of assent' becomes 'nod' (I've seen this in another clue).
'nod' written backwards gives 'don'.
'par'+'don'='PARDON'
'the' is the link.
(Other definitions for pardon that I've seen before include "Grant forgiveness" , "Forgive (an error)" , "Let off" , "Forgive, perhaps judicially" , "Forgiveness for an offence" .)