挿
ソウ, さ.す, はさ.む

insert, put in, graft, wear (sword)

JLPT1 G7 S10 F1908

As per 臿# (insert) + 手 hand/action indicator (for emphasis/clarification) → *insert*; *fit* → *graft* (a branch); *plant* (a cutting).

[Full Kanji Etymology List]