。
It's such a waste — you have a lawyer's license and everything.
Literal
Going-to-the-trouble-of lawyer [genitive-の] qualification [subject-が] exists [despite-のに] wasteful.
A single adjective does most of the work here — もったいない ('wasteful,' 'too good to let go to waste') — fronted by the set-up clause ending in のに ('despite'). せっかく is a hard-to-translate adverb meaning 'going to the trouble of,' 'despite the effort put in,' 'precious.' It flags the preceding fact as valuable or effortfully gained, and sets up a contrast where that value is about to be undermined. The pairing せっかく~のに~もったいない is a classic Japanese way of expressing regret over wasted potential: 'given how X, it's such a shame that Y.' Subject of 'it's a waste' is elided — context tells you what's being wasted.