To clean up means work for many (3)
I believe the answer is:
mop
'to clean up' is the definition.
(I've seen this in another clue)
'work for many' is the wordplay.
'work' becomes 'op' (common abbreviation for 'opus').
'for' means one lot of letters go next to another (I've seen this in other clues).
'many' becomes 'm' (Roman numeral for a thousand).
'op' after 'm' is 'MOP'.
'means' is the link.
(Other definitions for mop that I've seen before include "Shock of hair; soak (up)" , "Hair, unkempt" , "Floor wiper" , "Tangle of hair" , "It's used to wipe the floor" .)