Flourish as British operator starting off (7)
I believe the answer is:
burgeon
'flourish' is the definition.
(I've seen this in another clue)
'british operator starting off' is the wordplay.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'operator' becomes 'surgeon' (someone who operates).
'starting off' means to remove the first letter (the letter which starts the word is removed).
'surgeon' with its initial letter taken off is 'urgeon'.
'b'+'urgeon'='BURGEON'
'as' is the link.
(Other definitions for burgeon that I've seen before include "bud" , "Produce buds - flourish" , "swell" , "Grow and flourish" , "develop quickly" .)