We'll have no more of that! Plug up the hole (4,2)
I believe the answer is:
stop it
'we'll have no more of that plug' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'up the hole' is the wordplay.
'up' becomes 'sto' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'the hole' becomes 'pit' (pit is a kind of hole).
'sto'+'pit'='STOP IT'
Can you help me to learn more?
(Other definitions for stop it that I've seen before include "Desist!" , "Don't" .)