New dustmen are not sorted by academic ability (10)

I believe the answer is:

unstreamed

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

'new dustmen are not sorted by academic ability' is the definition.
I can't tell whether this definition defines the answer.

'new dustmen are' is the wordplay.
'new' indicates anagramming the letters.
'dustmen'+'are'='dustmenare'
'dustmenare' anagrammed gives 'UNSTREAMED'.

Can you help me to learn more?

I've seen this clue in The Independent.

Want a hint initially instead of a full solution? Install my app