The practice that can help you past your learned bad habits of trying to edit as you write is what Elbow calls "free writing." (07.6 Passage 2)
主干:The practice...is what...
定語從句that can...修飾主語The practice,從句中的介詞短語 past your...habits作賓語you的補語,as you write引導的時間狀語從句修飾trying to edite。what引導的表語從句中用了“call+賓語+補語”的結構,what是賓語,free writing是補語。