Wrong again, stands up to volunteer (5)
I believe the answer is:
offer
'volunteer' is the definition.
('offer' can be a synonym of 'volunteer')
'wrong again stands up' is the wordplay.
'wrong' becomes 'off' (I've seen this in other clues**).
'again' becomes 're'.
'stands up' says the letters should be written in reverse (I've seen 'stood up' mean this (in a down clue, letters go up)).
're' back-to-front is 'er'.
'off'+'er'='OFFER'
'to' is the link.
(Other definitions for offer that I've seen before include "Bid; proposal" , "Attempt" , "Propose (to give)" , "killer?" , "Sum of money proposed as payment" .)