Cancel visit that's not working (4,3)
I believe the answer is:
call off
'cancel' is the definition.
(I know that cancel can be written as call off)
'visit that's not working' is the wordplay.
'visit' becomes 'call' (synonyms).
'that's not working' becomes 'off' (switched off).
'call'+'off'='CALL OFF'
(Other definitions for call off that I've seen before include "Abandon" , "Cancel - summon away" , "Cancel or terminate - shout away" , "Order to desist" , "Cancel, order not to proceed" .)