Rebounding off the wall in shock (4)
I believe the answer is:
stun
'shock' is the definition.
(both can mean to surprise)
'rebounding off the wall' is the wordplay.
I cannot really understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is located in the answer.
The remaining letters 'sun' is a valid word which might be clued in a way I don't understand.
This explanation may well be incorrect...
'in' is the link.
Can you help me to learn more?
(Other definitions for stun that I've seen before include "Make senseless or dizzy with a blow" , "Daze, knock senseless" , "Daze, concuss" , "Stupefy - daze" , "Numb with nuts" .)