Customs officer looks here as a precaution (2,4)

I believe the answer is:

in case

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'as a precaution' is the definition.
(just in case)

I don't understand how the rest of the clue works.

(Other definitions for in case that I've seen before include "for emergency" , "As a precaution" , "For fear that" , "Packed" , "Where traveller may keep clothes" .)

I've seen this clue in the Sydney Morning Herald.

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