。
She has a habit of clearing her throat before speaking.
Literal
She [topic-は] speak [before-前に] throat-clearing do habit [subject-が] exists.
癖がある (くせがある, 'to have a habit/quirk') describes a persistent behavioral pattern. 咳払い (せきばらい, 'clearing one's throat') is a compound noun — 咳 (cough) + 払い (clearing away). The structure [verb plain form]+前に+[habit noun]+がある is a standard way to describe habitual pre-action behaviors.