Rubbish drawer, with mainly bags in it (7)
I believe the answer is:
doodler
'it' is the definition.
The definition suggests a singular noun which matches the answer.
'rubbish drawer with mainly bags' is the wordplay.
'rubbish drawer' becomes 'dr' (I can't explain this - if you can you should give a lot more credence to this answer).
'with' indicates putting letters inside.
'mainly' means to remove the last letter.
'bags' becomes 'oodles' (I've seen this before).
'oodles' with its last letter taken away is 'oodle'.
'dr' placed around 'oodle' is 'DOODLER'.
'in' acts as a link.
Can you help me to learn more?
(Other definitions for doodler that I've seen before include "One idly drawing" , "One scribbling" , "Idle sketcher?" , "linesman" , "Absent-minded scribbler" .)