Wife positioned outside to deliver blow (4)
I believe the answer is:
swat
'deliver blow' is the definition.
(I've seen this before)
'wife positioned outside' is the wordplay.
'wife' becomes 'w' (abbreviation).
'positioned' becomes 'sat' (sitting is a kind of positioning).
'outside' is an insertion indicator.
'w' placed inside 'sat' is 'SWAT'.
'to' is the link.
(Other definitions for swat that I've seen before include "land crushing blow" , "strike smartly" , "'Hit swiftly, a fly perhaps (4)'" , "Deal a quick and effective blow (to)" , "Hit (flies, etc)" .)