It holds the lead throughout (6)

I believe the answer is:

pencil

'it holds the lead throughout' is the definition.
(a pencil's graphite is often called its lead)

This is the entire clue.

(Other definitions for pencil that I've seen before include "writing equipment" , "Writing instrument" , "Drawing instrument" , "__-sharpener" , "Writing implement with graphite centre" .)

I've seen this clue in The Globe and Mail.

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