Rubbish left in public (6)
I believe the answer is:
litter
'rubbish left in public' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for litter that I've seen before include "mess around?" , "Brood of young born to an animal" , "Rubbish left in public places" , "Young dogs, perhaps" , "Bits of rubbish left lying about" .)