Harridan British PM once capturing adult vote (9)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

B (abbreviation for British) + ATTLEE (Clement Attlee, former UK Prime Minister = PM once), containing (capturing) A (abbreviation for adult) + X (symbol used to indicate a vote on a ballot paper). Harridan = battle-axe = disparaging term for a bad-tempered or strong-minded woman.