Fail-safe if I do troop manœuvres (5-5)

I believe the answer is:

idiot-proof

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'fail-safe' is the definition.
Both the answer and definition are adjectives.
Maybe there's an association between them I don't understand?

'if i do troop manoeuvres' is the wordplay.
'manoeuvres' is an anagram indicator.
'if'+'i'+'do'+'troop'='ifidotroop'
'ifidotroop' is an anagram of 'IDIOT-PROOF'.

Can you help me to learn more?

I've seen this clue in The Everyman puzzle in The Observer.

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