Crossword Genius

This hole designed to stash billions, in principle (10)

Ross

I believe the answer is:

shibboleth

'principle' is the definition.
(a principle shared by a certain group)

I cannot understand how the remainder of the clue works.

(Other definitions for shibboleth that I've seen before include "test word" , "Catchword, slogan" , "cultural custom" .)

I've seen this clue in The Times.
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