Cleaners start mucking out pig sties (4)
I believe the answer is:
mops
'cleaners' is the definition.
The answer and definition can be both man-made objects as well as being plural nouns.
Perhaps you can see an association between them that I don't see?
'start mucking out pig sties' is the wordplay.
'start' indicates taking the first letters.
The initial letters of 'mucking out pig sties' is 'MOPS'.
Can you help me to learn more?
(Other definitions for mops that I've seen before include "grimaces" , "They're used to clean floors" , "Swabs, wipes up" .)