Stagger round the bend to the left (4)
I believe the answer is:
stun
'stagger' is the definition.
(both can mean to shock)
'round the bend to the left' is the wordplay.
'round' is an insertion indicator.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'bend' becomes 'nus' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'to the left' says the letters should be written backwards (letters written from right to left).
't' put within 'nus' is 'nuts'.
'nuts' in reverse letter order is 'STUN'.
Can you help me to learn more?
(Other definitions for stun that I've seen before include "Concuss, stupefy" , "Put out for the count" , "floor" , "Shock or astonish" , "Daze or bewilder" .)