Stuck on:
23A No Munros are flake-free (8) ??S?A?E?
26A Latitude line (8) ??R?L?E? - Looks as though the first part might be CIRCLE, but I can't find an ending.
21D Apex (4) ???? - Could this be ACME or possibly PEAK. The second and fourth letters are the first letters of 23A & 26A.
Some hints please.