セイ, シン, ショウ, こ.う, う.ける, うけ

solicit, invite, ask

JLPT1 G7 S15 F524

青 here an abbreviated form# of pity + 言 words → *request* pity/charity → *ask*; *beg*. Also, *receive*; *undertake* and *(sub)contract* (← receive a request and undertake to respond), as well as *redeem* (← fulfill a pledge/undertaking).

[Full Kanji Etymology List]