Stop husband getting key (4)
I believe the answer is:
halt
'stop' is the definition.
(halt can mean to stop)
'husband getting key' is the wordplay.
'husband' becomes 'h' (abbreviation).
'getting' is a charade indicator (letters next to each other).
'key' becomes 'alt' (the Alt keyboard button).
'h'+'alt'='HALT'
(Other definitions for halt that I've seen before include "Limp; minor station" , "Pull up" , "Stop; minor station" , "Stop, small station" , "Cease" .)