Agree to provide answer after expression of surprise (10)
I believe the answer is:
correspond
'agree' is the definition.
(I've seen this before)
'answer after expression of surprise' is the wordplay.
'answer' becomes 'respond' ('respond' can be a synonym of 'answer'**).
'after' says to put letters next to each other.
'expression of surprise' becomes 'cor' (I've seen this before).
'respond' put after 'cor' is 'CORRESPOND'.
'to provide' acts as a link.
(Other definitions for correspond that I've seen before include "Communicate; agree" , "email, say?" , "Exchange letters" , "Have a close similarity" , "Swap letters" .)