Mess made by lots of little pigs (6)
I believe the answer is:
litter
This clue is a double definition.
'mess' is the first definition.
(thesaurus)
'lots of little pigs' is the second definition.
(litter of piglets)
'made by' acts as a link.
(Other definitions for litter that I've seen before include "Bits of rubbish left lying about" , "waste material" , "junk" , "Number of young animals born at one time" , "Offspring of a multiple birth" .)