Crossword Genius

Something used for wiping bum (6)

Ross

I believe the answer is:

sponge

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'bum' is the definition.
(take money from someone without reciprocating)

I can't explain the rest of the clue.

Can you help me to learn more?

(Other definitions for sponge that I've seen before include "Freeload" , "Wipe" , "'Porous, absorbent substance (6)'" , "Bathroom scrubber" , "mop" .)

I've seen this clue in The Independent.
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