Stewards' enquiry, say? It's routine (1,6,2,6)

I believe the answer is:

a matter of course

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'routine' is the definition.
(I've seen this before)

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

(Other definitions for a matter of course that I've seen before include "Someone covering Aintree" , "routine" .)

I've seen this clue in The Telegraph.

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