I really love the idea of echoing clues, as in Youngster/Youngsters and Shallow sea/Deep sea. I do wonder about some of the grammar for these; 5A, for instance, I'm fine with because the superfluous red almost seems like a joke on the phrase, but I'm less sure what's happening in 2A (looks like a double deletion and anagram, but I only see a possible hidden indicator). I might just be misinterpreting these, and if so, feel free to ignore me with my apologies! Other slight rule-benders: in 2D, if you're reversing a hidden with "keeps" and "up," many solvers prefer the answer to be entirely hidden within something, so using all of "deep" in this case is a bit off. In 3D, a deletion is usually taken as a whole or at least in order, not as a series of letters. I think logically you should be able to do this, especially since everything else is direct, but YMMV. Thanks for the solve!
I hate to be negative but so many conventional rules have been broken here that one could hardly call this a cryptic. I mean, does "lead" (singular) really mean the first letterS of the words seen prior? Not to me.