Those going on walks they go on? (8)

I believe the answer is:

ramblers

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'they go on?' is the definition.
(I've seen this before)

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

(Other definitions for ramblers that I've seen before include "Rovers, walkers" , "they go on walks!" , "Long-distance walkers" , "see them traversing fields?" .)

I've seen this clue in The Independent.

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