Returned with pen, but he's last (4,6)

I believe the answer is:

back marker

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'he's last' is the definition.
The definition suggests a singular noun which matches the answer.

'returned with pen' is the wordplay.
'returned' becomes 'back' (I've seen this in other clues).
'with' says to put letters next to each other.
'pen' becomes 'marker' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'back'+'marker'='BACK MARKER'

'but' acts as a link.

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I've seen this clue in The Daily Express.

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