For each side upon tumbling meteor (7)

I believe the answer is:

perseid

'meteor' is the definition.
(the Perseids are a meteor shower)

'for each side upon tumbling' is the wordplay.
'for each' becomes 'per' (I've seen this before).
'upon tumbling' is an anagram indicator (letters tumble around).
'side' with letters rearranged gives 'seid'.
'per'+'seid'='PERSEID'

(Another definition for perseid that I've seen is " Annual meteor shower".)

I've seen this clue in The Guardian.

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