Instrument carried in this larger one as a precaution (6,4)

I believe the answer is:

violin case

'instrument carried in this' is the definition.
(case for a musical instrument)

'larger one as a precaution' is the wordplay.
'larger one' becomes 'viol' (I am not sure about this - if you are sure you should believe this answer much more).
'as a precaution' becomes 'in case' (just in case).
'viol'+'incase'='VIOLIN CASE'

(Another definition for violin case that I've seen is " Fiddle box".)

I've seen this clue in The Guardian.

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