Well-timed play on words tops off material (8)

I believe the answer is:

punctual

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'well-timed' is the definition.
Both the answer and definition are adjectives. Maybe there's an association between them I don't understand?

'play on words tops off material' is the wordplay.
'play on words' becomes 'pun' (synonyms).
'tops off' means to remove the first letter (I've seen 'top off' mean this).
'material' becomes 'actual' (both can mean real).
'actual' with its first letter removed is 'ctual'.
'pun'+'ctual'='PUNCTUAL'

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(Other definitions for punctual that I've seen before include "Arriving on time" , "Exactly on time" , "Bang on time" , "Happening at the agreed time" , "Always on time for appointments" .)

I've seen this clue in The Irish Times.

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