弱起 is read as じゃっき (jakki) and means anacrusis.
じゃっき
jakki
じゃくてん
weak point
よわき
bearish
よわみ
(a) weakness
よわい
weak
よわね
feeble complaint
よわまる
to abate
よわめる
to weaken
よわる
to be downcast
よわむし
coward
よわぶくみ
bearish tendency
よわごし
weak attitude
じゃくたい
weak (organization, organisation)