compel, pressure, force, bother
偪 centers on applying strong pressure to make someone act: compelling, forcing, or bothering them until they yield.
偪 combines 亻 (person) with 畐, which likely contributes the sound and may relate to fullness or pressure. The exact historical development is uncertain.
A person 亻 beside 畐, which looks like a container being filled to the brim, suggests someone being pressured or forced into a tight spot.
For フク, imagine a person being forced to wear a bulky fuku (服, clothing) that is too tight, pressuring them: fuku -> フク.