Hush as the French entered (7)
I believe the answer is:
silence
'hush' is the definition.
(I know that hush can be written as silence)
'as the french entered' is the wordplay.
'as' becomes 'since' (both can mean 'because').
'the french' becomes 'le' ('the' in French).
'entered' means one lot of letters goes inside another.
'since' going around 'le' is 'SILENCE'.
(Other definitions for silence that I've seen before include "Noiselessness" , "may be required in court" , "that's golden" , "Quietness" , "Nothing said" .)