City abandoning cleaner strip (7)

I believe the answer is:

undress

I'm a little stuck... Click here to teach me more about this clue!

'strip' is the definition.
(I know that strip can be written as undress)

I cannot understand how the remainder of the clue works.

Can you help me to learn more?

(Other definitions for undress that I've seen before include "Remove clothes, strip" , "Nudity" , "Divest of clothes" , "Strip, take off clothes" , "Take one's clothes off" .)

I've seen this clue in The Telegraph.

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