Rubbish kittens, say (6)
I believe the answer is:
litter
This might be a double definition.
'rubbish' is the first definition.
(litter is a kind of rubbish)
'kittens say' is the second definition.
'litter' can be an answer for 'kittens' (I've seen this before). I'm unsure of the 'say' bit.
Can you help me to learn more?
(Other definitions for litter that I've seen before include "dropped by louts?" , "Pups - bedding - stretcher" , "Scattered rubbish" , "little ones?" , "Little pigs, for example" .)