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 quite understand how this works, but
'the' could be 't' (the is pronounced as a 't' sound in some dialects) and 't' is found within the answer.
The remaining letters 'sun' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
'in' acts as a 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" .)