Insects — two of them in rubbish (4)
I believe the answer is:
bees
I believe this clue is a double definition.
'insects' is the first definition.
(bee is a kind of insect)
'two of them in rubbish' is the second definition.
(the word 'rubbish' has two B's)
(Other definitions for bees that I've seen before include "Social insects" , "Apiary inhabitants" , "Four-winged insects" , "Honey makers" , "Honey-producing insects" .)