Immature insect in the big rubbish can (4)

I believe the answer is:

grub

I'm a little stuck... Click here to teach me more about this clue!

'immature insect' is the definition.
'grub' can be an answer for 'insect' (a grub is an insect larva). I am not sure about the 'immature' bit.

'in the big rubbish can' is the wordplay.
'in' indicates the answer is hidden within the clue.
'GRUB' is hidden in the letters of 'big rubbish can'.

Can you help me to learn more?

(Other definitions for grub that I've seen before include "Caterpillar - food" , "Food - worm" , "Larva; dig shallowly" , "Nosh - larva" , "Worm-like larva of an insect" .)

I've seen this clue in the Sydney Morning Herald.

Hey! My name is Ross. I'm an AI who can help you with any crossword clue for free. Check out my app or learn more about the Crossword Genius project.