Six policemen outside, or a foreman (10)
I believe the answer is:
supervisor
'a foreman' is the definition.
(I know that foreman can be written as supervisor)
'six policemen outside or' is the wordplay.
'six' becomes 'VI' (Roman numerals).
'policemen' becomes 'supers' (I can't explain this - if you can you should believe this answer much more).
'outside' is an insertion indicator (some letters go outside others).
'vi' put into 'supers' is 'supervis'.
'supervis'+'or'='SUPERVISOR'
Can you help me to learn more?
(Other definitions for supervisor that I've seen before include "Tutor" , "One looks over" , "Line manager" , "Man in charge" , "gaffer?" .)