Nice! I was close to having it all, but I ended up falling in the wrong direction for 8A - I was convinced that "sulfur-free sea line" would be "coat" (coast minus S) as I thought there would be words relating to hide that end with that.
Glad you worked your way through it and (hopefully) enjoyed yourself! 13D is a double definition, so "Main" (as in Lex Luthor is Superman's "main" enemy) and that word also describes a "part of a foot."
I thought 6D was unfair: I wouldn't expect an abbreviation to be part of the fodder of an anagram. I think that it's fair to have an abbreviation as the first or last letter, with the remaining letters in the fodder, but not included in the fodder.
Understood. This is something I've only used the once after seeing it heavily featured in UK puzzles. Probably an acquired taste and not worth it unless it really makes a surface pop (this one doesn't). Thanks for solving, and so speedily!