56ac. Marks entrance for racecourse (6,5). Looked up racecourses(?) and could only find Market Rasen but could not parse it. And it does not work with the down clues in that area. We are stuck in that bottom LH corner and won't allow ourselves to start on 1136 until 1135 is finished!
So which of the two is it? I can see the parsing of Market Rasen - anagram of first 11 letters - (but how/why those? Is that 'entrance'), and that does not give me a 'D' as a last letter of 34d which we think is 'jet-propelled'. Brands Hatch does, but how does that parse? Still puzzled.