Shock as potty is overturned (4)
I believe the answer is:
stun
'shock' is the definition.
(both can mean to surprise)
'potty is overturned' is the wordplay.
'potty' becomes 'nuts' (I've seen this before).
'is overturned' shows that the letters should be reversed in order.
'nuts' backwards is 'STUN'.
'as' acts as a link.
(Other definitions for stun that I've seen before include "Confuse" , "Leave speechless" , "Concuss; amaze" , "Bowl over" , "Numb with nuts" .)