partial, side, left-side radical, inclining, biased
JLPT1 G7 S11 F1340
As per 扁# (spread, but remain in contact) + 人 person (→ human agency) → *lean*; *incline* → *partiality*; *bias*. *Element at the left of a Han/Chinese character* is a borrowed meaning, via 扁.
[Full Kanji Etymology List]