Drxx - thanks for this contribution to the title - title jungle; reminds me of the subltle but fundamental difference between one of the synonyms being used as legal justification locally of releasing Green Belt land for development - and another revealing the real motive.
Of course, English being the rich pudding that it is, the setter can find ample justification for his thematic treatment converting the song title to the puzzle title - but we are directed to
Chambers as the ultimate authority, not Will Shakespeare, and for me the process remains paradoxical.
Thepost - you say "Puzzle finally finished (even if I do not understand the synonyms and homophone business)..."
are you absolutely sure you've finished? Have you changed the single letter, and highlighted the 5 thematic words in the finished grid, as instructed in the preamble?
I don't see how you can have done that if you don't understand the thematic synonyms and homophones.