urge, force, imminent, spur on
逼 centers on applying pressure to compel action: urging someone forward, forcing a situation, or describing something imminent that closes in and demands a response.
逼 combines 辶 (movement) with 畐, which likely contributes the sound and carries a sense of fullness or pressure, together suggesting pressing forward or closing in.
The movement radical 辶 surrounds 畐, a shape associated with fullness. Picture a crowd pressing in from behind, forcing you to move forward urgently.
For フク, imagine being forced to wear a bulky fuku (服, clothing) that is too tight, urging you to move and get it off: fuku -> フク.