Same character as third-tone piě, the left-falling stroke, but a different word. First-tone piē means to cast aside: 撇开 to leave aside, 撇下 to abandon. If something is being dropped or ignored, the reading is piē.
usage
Two everyday uses sit under this reading. 撇开 and 撇下 push a person or a topic out of the way, often with a cold edge. In the kitchen it is the ladle word: you 撇 the foam or the grease off the top of a soup.
Left hand radical, the side-form of 手, and the indexing element. For this reading it marks a hand pushing something out of the way or lifting foam off the top, the same family as 抛 (throw) and 拨 (push aside).
Right side 敝 is the phonetic, bì drifting to piē. The same series gives 瞥 (to glance), which keeps both the sound and the sense of something brushed quickly past.