AJT-3d-Flora,fauna and everything on site -it is assemblage (archaeological site)
17d-It produces a blast or another with heart transplant-TROMP
Re the theme think of a symbol for each word making another
word.
Perhaps you could help with 4d-One European wild cherry at sea(6)
Even with theme word -not having Brewers I am labouring on the unclued lights!