チャンスを窺う is read as ちゃんすをうかがう (chansuoukagau) and means to wait for an opportunity.
ちゃんすをうかがう
chansuoukagau
虎視眈々とチャンスを窺う。
こしたんたんとちゃんすをうかがう。
To watch vigilantly for a chance.