On the wagon and drug free - what's to launder?

I believe the answer is:

dry-clean

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(Other definitions for dry-clean that I've seen before include "Wash without water" , "Remove dirt from clothes using solvents" , "Remove dirt from fabric using solvent" , "Use chemical solvent on clothes" , "Use an organic solvent to remove stains" .)

I've seen this clue in the Irish Times.

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