Instrument hit accidentally in research establishment (7)

I believe the answer is:

cithern

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'research establishment' is the definition.
I know nothing about this answer so I cannot tell whether this works.

'instrument hit accidentally in' is the wordplay.
'instrument' becomes 'cern' (I can't justify this - if you can you should give a lot more credence to this answer).
'accidentally' indicates anagramming the letters (a chaotic or accidental ordering of the letters).
'in' means one lot of letters goes inside another.
'hit' anagrammed gives 'ith'.
'cern' enclosing 'ith' is 'CITHERN'.

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I've seen this clue in The Guardian.

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