Bon jour! here 매달리다 means 어떤 것을 붙잡고 늘어지다. 집착하다 It means "stock to, cling to" 대학(진학)에 매달리다 means "stick to entering college"

The sentence means "You(assuming) value getting into college too much." ~에 매달리다 is sometimes used to describe situations when sb takes too much effort in sth. It implies the behavior doesn't seem positive to the speaker.(not worth it, etc) ex) 그 논쟁에 매달리는 것은 생산적이지 않다. It is not productive to put too much effort into the arguing. 그 일에 매달릴 바에 차라리 잠을 자겠다. I would rather sleep instead of working on that.