Be quiet because occupied by the French (7)
I believe the answer is:
silence
'be quiet' is the definition.
(both are said to tell someone to stop speaking)
'because occupied by the french' is the wordplay.
'because' becomes 'since' (both can mean as a result of).
'occupied by' indicates putting letters inside.
'the french' becomes 'le' ('the' in French).
'since' enclosing 'le' is 'SILENCE'.
(Other definitions for silence that I've seen before include "Quietness" , "Secrecy; stillness" , "Nothing said" , "License (anag)" , "Quietude" .)