Presumptuous newcomer (7)

I believe the answer is:

upstart

(Other definitions for upstart that I've seen before include "Person risen to high position, arrogant with it" , "Presumptuous and arrogant type" , "Over-assertive newcomer" , "Arrogant person new in high position" , "Pipsqueak" .)

I've seen this clue in The Times.

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