フク, ふ.せる, ふ.す, ふし, ふせ
prostrated, bend down, bow, cover, lay (pipes)
JLPT1 G7 S6 F1604
犬 here an abbreviated form# of 犾 as described in 獄 (pair of dogs) + 人 person → pair of dogs lying curled at their master's feet → *bend/lie down*; *cover (up)*; *hide*; *obey* (← all actions commonly associated with dogs) → *bow*; *prostrate oneself*; *turn over*; *lower*; *cast down*; *lay an ambush*.
[Full Kanji Etymology List]