Roof, most of the answer to 17a is the name of a well known comic book hero (6 letters) so you should see that fairly easily if you have the right answer.
17d is a musician variety of player. Constructed from a 3 letter word with a 5 letter word after it.
19a is two letters (that I don’t understand!) followed by an anagram of two of the words in the clue. The answer is a weird word that I have never seen before...
Good luck! Come back for more derailed hints if you need to