Prepared to explode - or not to explode (5)

I believe the answer is:

fused

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'prepared' is the definition.
Both the definition and answer are adjectives. Perhaps there's an association between them I don't understand?

I don't understand the rest of the clue.

Can you help me to learn more?

(Other definitions for fused that I've seen before include "Married" , "Joined by melting" , "Combined" , "Welded together by heat" , "Coalesced" .)

I've seen this clue in The Irish Independent, The Globe and Mail and The Irish News.

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