Instrument computing time in research facility (7)

I believe the answer is:
cittern
'facility' is the definition.
Both the definition and answer are singular nouns.
Maybe there's a link between them I don't understand?
I don't understand how the remainder of the clue works.
Can you help me to learn more?
(Another definition for cittern that I've seen is " it used to be plucked".)
I've seen this clue in The Sunday Times and The Times.
Want a hint initially instead of a full solution?
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