Press going through borders work together (4,6)

I believe the answer is:

join forces

'work together' is the definition.
(to join forces with someone is to work with them)

'press going through borders' is the wordplay.
'press' becomes 'force' (I've seen this in other clues).
'going through' indicates putting letters inside.
'borders' becomes 'joins'.
'force' placed within 'joins' is 'JOIN FORCES'.

I've seen this clue in The Guardian.

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