。
She bent at the waist.
Literal
She [topic-は] hips [object-を] bent.
腰をかがめる ('bend at the waist, stoop') uses かがめる as the transitive verb meaning 'to bend, to stoop down' — the intransitive かがむ means 'to crouch, to bend down.' 腰 ('lower back, hips') is the body part identified in Japanese as the seat of bending and posture, and many phrases use it metaphorically: 腰が低い ('humble, deferential'), 腰が引ける ('lose nerve'), 腰を据える ('settle in'). The simple past かがめた suggests a discrete action — perhaps to pick something up, peer at something, or bow.