Get away at one in punt (4,2)
I believe the answer is:
beat it
'get away' is the definition.
('beat it!' means get away)
'at one in punt' is the wordplay.
'one' becomes 'i' (Roman numeral).
'in' means one lot of letters goes inside another.
'punt' becomes 'bet' (I've seen this in other clues).
'at'+'i'='ati'
'ati' going inside 'bet' is 'BEAT IT'.
(Other definitions for beat it that I've seen before include "fly away" , "try out drum kit?" , "Slang order to go away, get lost" , "Get going" , "Clear off!" .)