I have an answer for 17d, Having emptied symbol for this element (7). I have MERCURY, but can only match it with the 'element' part of the clue. An explanation would be appreciated.
stuck on 2
15a: Treat to circular cheese back inside (7) ???O?T?
14d: Winning eal from the horse's mouth (5-4) ???S?-H?N
I think 14d is First-hand but not sure why...
Help please on 14d: Limit a dish swallowed by salmon (9) ?A?A?E?E?
I have an answer which fits the definition of limit, but cannot see how it fits the rest of the clue...