It should have a safety pin in it (7)

I believe the answer is:

grenade

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'it should have a safety pin in it' is the definition.
The definition suggests a singular noun which matches the answer.

This is the entire clue.

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(Other definitions for grenade that I've seen before include "Angered (anag)" , "Missile thrown" , "Handy bomb" , "Small hand-bomb" , "Small bomb thrown by hand" .)

I've seen this clue in The Globe and Mail.

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