Unidentified thing with energy quota cropping up again? (9)

I believe the answer is:

iteration

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'cropping up again?' is the definition.
I can't tell whether this definition defines the answer.

'unidentified thing with energy quota' is the wordplay.
'unidentified thing' becomes 'it' (I am not sure about the 'unidentified' bit.).
'with' is a charade indicator (letters next to each other).
'energy' becomes 'e' (physics symbol as in E=mct).
'quota' becomes 'ration' (I've seen this before).
'it'+'e'+'ration'='ITERATION'

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(Other definitions for iteration that I've seen before include "Repeating" , "Repetition" , "Repeats" , "Reprise" , "Repeated performing" .)

I've seen this clue in The Independent.

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