Goofy expression curtailed time in charge (7)

I believe the answer is:

idiotic

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'goofy' is the definition.
(thesaurus)

'expression curtailed time in charge' is the wordplay.
'expression' becomes 'idiom' (idiom is a kind of expression).
'curtailed' means to remove the last letter.
'time in charge' becomes 'tic' (this could be a standard abbreviation of which I'm unaware).
'idiom' with its final letter taken off is 'idio'.
'idio'+'tic'='IDIOTIC'

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(Other definitions for idiotic that I've seen before include "Altogether nonsensical" , "Silly" , "Ridiculous" , "Mindless" , "Absurd, crackbrained" .)

I've seen this clue in The Independent.

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