Small lengths of chalk had ends removed by songbirds (4-6)

I believe the answer is:

half-inches

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

'chalk had ends removed by songbirds' is the definition.
I don't know anything about this answer so I cannot tell whether this works.

'small lengths' is the wordplay.
'small' becomes 'half' (I can't justify this - if you can you should believe this answer much more).
'lengths' becomes 'inches' (I have seen 'Short lengths ' mean 'inches' so perhaps 'lengths' could also mean 'inches').
'half'+'inches'='HALF-INCHES'

'of' acts as a link.

Can you help me to learn more?

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.