Right:
I've got a full grid, I understand the combination of (a) and the title, and how this is common to the answers to the normal clues, all three of which I know and have parsed.
I also understand the non-verbal symbolic entries in the six crossword lights making up these three answers, and know that these correspond correctly (if only incompletely) to the respective verbal versions of the answers.
I also understand that (b) is a play on the theme clued cryptically by Lionheart in the preamble, and that it implies that the substitution mentioned should involve transposition of two or more of the three "normal" clue answers.
I also understand and have entered 18d, 12d (important in a field I've been active in for 65 years - though evidently not to everyone's taste) - although this clashes in four places with the symbolic entries of the normal clue answers (with letters making up a conceivably thematic 4-letter word).
My problem is that I can make nothing that I can comprehend with (c) - I'm missing two of the 9 extra letters, from 30d and 33d - I've guessed the entries/definitions, but the wordplay of both defeats me - and the 7 letters that I am sure of resist all my attempts at decoding.
I hope I haven't given too much away, and that some kind soul can find a way to subtly nudge me towards enlightenment that will also not give too much away.
Hope 1a was nice to you all.