Idiomatic expression meaning to trip someone up, undermine them, or pull the rug out from under them (often by unexpected action).
ライバル会社が新しい割引戦略で我々の足をすくおうとしている。
A rival company is trying to trip us up with a new discount strategy.
彼は重要な場面で足をすくわれて、契約を失った。
He was tripped up at a crucial moment and lost the contract.
上司が陰で部下の足をすくっていたことが発覚した。
It was discovered that the boss had been undermining his subordinate behind the scenes.