Quiet commissionaire misses nothing, given time (7)
I believe the answer is:
dormant
'quiet' is the definition.
(similar in meaning)
'commissionaire misses nothing given time' is the wordplay.
'commissionaire' becomes 'doorman' (commissionaire can mean a doorman).
'misses' indicates named letters should be taken away.
'nothing' becomes 'O' (O resembles 0).
'given' is a charade indicator (letters next to each other).
'time' becomes 't' (abbreviation).
'doorman' with 'o' removed is 'dorman'.
'dorman'+'t'='DORMANT'
(Other definitions for dormant that I've seen before include "Hibernating" , "Latent" , "Sluggish" , "In deep sleep" , "Inert" .)