Felt-tip produced by one keeping score by enclosure (6,3)

I believe the answer is:

marker pen

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'felt-tip' is the definition.
(I've seen this before)

'by one keeping score by enclosure' is the wordplay.
'by one keeping score' becomes 'marker' (I can't justify this - if you can you should give a lot more credence to this answer).
'by' is a charade indicator (letters next to each other).
'enclosure' becomes 'pen' (pen is a kind of enclosure).
'marker'+'pen'='MARKER PEN'

'produced' acts as a link.

Can you help me to learn more?

(Another definition for marker pen that I've seen is " felt-tip".)

I've seen this clue in The Telegraph.

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