Suspect Padraig's stealing Henry's copying instruments (9)

I believe the answer is:

diagraphs

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'copying instruments' is the definition.
I don't know anything about this answer so I can't tell whether it can be defined by this definition.

'suspect padraig's stealing henry's' is the wordplay.
'suspect' indicates an anagram (a suspicious or unusual spelling).
'stealing' is an insertion indicator.
'henry' becomes 'H' (symbol for the unit of electrical inductance).
'padraigs' with letters rearranged gives 'diagraps'.
'diagraps' going around 'h' is 'DIAGRAPHS'.

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I've seen this clue in The Independent.

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