Sunburnt feature of black snake (3,5)

I believe the answer is:

red belly

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

'sunburnt feature of black snake' is the definition.
I can't tell whether this definition defines the answer.

'sunburnt feature of black snake' is the wordplay.
'sunburnt' becomes 'red' (I've seen this in another clue).
'feature of black snake' becomes 'belly' (I can't explain this - if you can you should believe this answer much more).
'red'+'belly'='RED-BELLY'

Can you help me to learn more?

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

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