Crossword Genius

Soldier on set I look to knock over (4,2,2)

Ross

I believe the answer is:

keep it up

'soldier on' is the definition.
(to soldier on at something is to keep it up)

'set i look to knock over' is the wordplay.
'set' becomes 'put' (synonyms).
'look' becomes 'peek' (peek is a kind of look).
'to knock over' says the letters should be written in reverse.
'put'+'i'+'peek'='putipeek'
'putipeek' back-to-front is 'KEEP IT UP'.

(Another definition for keep it up that I've seen is " words of encouragement".)

I've seen this clue in The Guardian.
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