6, 9 and 15 are all thematic. Giving you the longer answers might be too revealing, and I don't know if you'd want to get there by yourself? Oh, and I think the theme might be very UK-ish!
10 The answer is a tree family, one of those botanical words. Some anagramming is involved (and the 'serve' is in tennis).
10a extra is 'a' from the anagram 'me[a]l I' + another word for 'serve' (tennis) + AE (Scots 'one').
14a extra 's' - '[s]take' = R ('state' is a typo).
6d extra 'f' '[f]ate'
9 extra 'm' 'sa[m]e'
Thanks NAC and ProfessorM.
I had ane for one in 10. Now solved.
What is Identifier in 1d?
6d. I can get meat consumers but the 4th letter is extra so parsing?
Hints on 11d, 28d and 31dinstead of the thematic ones.
11d - the def is '[b]reached'.
28d 'horsepower in German' is abbrev PS (def 'particle').
31d extra 'o' '[o]bit of Byzantine Empire' is the def for a region - but 'topic' is another synonym (this 'bit' was new to me, hankir).