rub, stroke with hands, crumple
挼 centers on applying pressure with the hands to manipulate something: rubbing, stroking, or crumpling.
挼 combines 扌 (hand) with 妥, which likely contributes the sound. The exact historical development is uncertain, but the structure suggests a hand action related to the meanings.
The hand radical 扌 beside 妥 (which looks like a hand over a woman) suggests hands working something: rubbing, stroking, or crumpling.
For ダ, imagine rubbing a piece of dough with your hands: dough -> ダ, and the action of rubbing matches the kanji's meaning.