Triggered grotesque dieting (7)

I believe the answer is:

ignited

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'triggered' is the definition.
Although both the answer and definition are past participle verbs, I cannot understand how they can define each other.

'grotesque dieting' is the wordplay.
'grotesque' indicates anagramming the letters.
'dieting' is an anagram of 'IGNITED'.

Can you help me to learn more?

(Other definitions for ignited that I've seen before include "Kindled" , "fired" , "Gin diet (anag.)" , "Set alight" , "Caught fire" .)

I've seen this clue in The Daily Express.

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