On being consumed by deluge, flattened (7)

I believe the answer is:

floored

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'flattened' is the definition.
Both the definition and answer are adjectives. Maybe they are linked in a way I don't understand?

'on being consumed by deluge' is the wordplay.
'on' becomes 're' (regarding).
'being consumed by' means one lot of letters goes inside another (inserted letters get consumed).
'deluge' becomes 'flood' (synonyms).
're' inserted inside 'flood' is 'FLOORED'.

Can you help me to learn more?

(Other definitions for floored that I've seen before include "stumped" , "Knocked out" , "Greatly surprised" , "Threw" , "Completely baffled" .)

I've seen this clue in The Telegraph.

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