The Roman way of getting from Exeter to Lincoln (5)

I believe the answer is:

fosse

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

I can't explain the rest of the clue.

(Other definitions for fosse that I've seen before include "Long trench or ditch" , "-- Way, Roman road" , "Long narrow ditch" , "Fortified moat" , "Long, narrow trench or excavation" .)

I've seen this clue in the Evening Standard.

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