Dawn French for one tucked into drink (5)
I believe the answer is:
sunup
'dawn' is the definition.
(synonyms)
'french for one tucked into drink' is the wordplay.
'french for one' becomes 'un' ('one' in French).
'tucked into' means one lot of letters goes inside another.
'drink' becomes 'sup' (to sup is to drink).
'un' going inside 'sup' is 'SUNUP'.
(Other definitions for sunup that I've seen before include "when a new day dawns" , "early in America" , "Dawn (American)" , "First light (US), rhymes with travelling over one hundred mph" , "Daybreak (in America)" .)