Complete failures if treated as lettuce (7)

I believe the answer is:

fiascos

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'complete failures' is the definition.
The definition and answer can be both related to natural events as well as being plural nouns.
Maybe they are linked in a way I don't understand?

'if treated as lettuce' is the wordplay.
'treated' indicates anagramming the letters.
'lettuce' becomes 'cos' (cos is a kind of lettuce).
'if' with letters rearranged gives 'fi'.
'fi'+'as'+'cos'='FIASCOS'

Can you help me to learn more?

I've seen this clue in the Evening Standard.

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