If under pressure, get going again (9)

I believe the answer is:

presuming

'if' is the definition.
('presuming' can mean if certain conditions apply)

'under pressure get going again' is the wordplay.
'under' says to put letters next to each other.
'pressure' becomes 'p' (abbreviation).
'get going again' becomes 'resuming' (to resume is to start doing something again).
'p' next to 'resuming' is 'PRESUMING'.

(Another definition for presuming that I've seen is " Taking for granted".)

I've seen this clue in The Guardian.

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