Old record is included in contracts for rock cognoscenti? (10)

I believe the answer is:

geologists

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'contracts for rock cognoscenti?' is the definition.
I can't judge whether this definition defines the answer.

'old record is included in' is the wordplay.
'old' becomes 'o' (abbreviation).
'record' becomes 'log' (log is a kind of record).
'is included' becomes 'geists' (I am not sure about this - if you are sure you should believe this answer much more).
'in' is an insertion indicator.
'o'+'log'='olog'
'olog' inserted inside 'geists' is 'GEOLOGISTS'.

Can you help me to learn more?

(Another definition for geologists that I've seen is " Rock fans".)

I've seen this clue in The Guardian.

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