Worthless blowtorch forms alliance (4)

I believe the answer is:

bloc

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'alliance' is the definition.
(I know that bloc is a type of alliance)

I cannot understand how the rest of the clue works.

Can you help me to learn more?

(Other definitions for bloc that I've seen before include "united nations" , "Group of countries with a shared aim" , "Nations grouped for a purpose" , "Allied group of countries or political parties" , "Combination of parties or countries" .)

I've seen this clue in The Irish Times.

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