Today's setter -- poor or rusty? Occasionally dull? Variable? (5,5)

I believe the answer is:

yours truly

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'today's setter' is the definition.
I don't know anything about this answer so I cannot judge whether it can be defined by this definition.

'poor or rusty? occasionally dull? variable?' is the wordplay.
'poor' indicates an anagram.
'occasionally' indicates alternate letters.
'variable?' becomes 'y' (algebra).
The alternate letters of 'dull' are 'ul'.
'or'+'rusty'='orrusty'
'orrusty' anagrammed gives 'yourstr'.
'yourstr'+'ul'+'y'='YOURS TRULY'

Can you help me to learn more?

(Other definitions for yours truly that I've seen before include "Myself, ironically" , "Nimrod" .)

I've seen this clue in The Telegraph.

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