Go on to suffer setback (3)
I believe the answer is:
yap
'go on' is the definition.
(both can mean to talk at length)
'suffer setback' is the wordplay.
'suffer' becomes 'pay'.
'setback' says the letters should be written in reverse.
'pay' written backwards gives 'YAP'.
'to' acts as a link.
(Other definitions for yap that I've seen before include "Pay up for chatter" , "Chatter at length" , "Yelp" , "Shrill bark; rhymes with chart" , "gossip -" .)