Pounds raised in Ulster — British in search for weapon (7,4)

I believe the answer is:

cluster bomb

'weapon' is the definition.
(I've seen this before)

I can't explain the rest of the clue.

(Other definitions for cluster bomb that I've seen before include "Weapon comprising numerous projectiles" , "Weapon with submunitions" , "lethal weapon" .)

I've seen this clue in The Times.

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