Pass for a senior officer (3)

I believe the answer is:

col

This clue is a double definition.

'pass' is the first definition.
(col is a term for a mountain pass)

'for a senior officer' is the second definition.
(abbreviation for colonel)

(Other definitions for col that I've seen before include "Pass between mountain ridges" , "Officer" , "Low point of saddle between two peaks" , "A depression in mountain range" , "Low point of a ridge" .)

I've seen this clue in the Evening Standard.

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