... the French, less than clean (7)
I believe the answer is:
launder
'clean' is the definition.
(I know that launder is a type of clean)
'the french less than' is the wordplay.
'the french' becomes 'la' ('the' in French).
'less than' becomes 'under' (eg under a certain number).
'la'+'under'='LAUNDER'
(Other definitions for launder that I've seen before include "Cleanse (material or money)" , "Led a run (anag)" , "Wash, starch and iron" , "Clean, clothes or mafia money" , "Make clean, clothing or money" .)