Weaken over time, as support

ERODE

Think of how water gradually wears away rock or how trust can slowly fade—this word describes that kind of steady decline.

"Weaken over time, as support" hints at something gradually wearing away, which is what "erode" means. The word often describes how water or wind breaks down rocks or land, but here it’s used more broadly—like trust or backing fading slowly. No wordplay or tricks; it’s a straightforward definition clue pointing to a common verb.