Godan verb with 'mu' ending, Transitive verb
to apply for; to make an application; to propose (marriage); to offer (mediation); to make an overture (of peace); to challenge; to lodge (objections); to request (an interview); to subscribe for; to book; to reserve
あなたはあの勤め口に申し込むべきだ。You should apply for that post.
Also written 申込む【もうしこむ】