Execute witch around noon (4)
I believe the answer is:
hang
'execute' is the definition.
(hanging is a kind of executing)
'witch around noon' is the wordplay.
'witch' becomes 'hag' ('hag' can be a synonym of 'witch').
'around' means one lot of letters goes inside another.
'noon' becomes 'n'.
'hag' placed around 'n' is 'HANG'.
(Other definitions for hang that I've seen before include "Suspend (something)" , "Hover" , "Suspend, perhaps execute" , "Be suspended" , "Kill with a noose" .)