Straight-forward fill - but wordplay for 22A (answer seems obvious) eludes me 'summary of betting odds with exchange of vocal elements' ... does SP come into it? ...
Crates, I think it's a slightly stretched 'sounds like' clue - if you say the Summary out loud and the Betting Odds (also meaning costs) out loud, the vowel parts/sounds changes.
23a Don helps to fill this freshly-made slab cake (5,3). The answer looks like Black Sea. I realise this is an anagram of slab cake but can't parse the rest of the clue?