The trouble with hidden letter puzzles is that there are often unintended/red herring ambiguities.
I am afraid that I am not completely happy with the solutions so far so can I suggest another possibility?
My dictionary lists "canter" as another word for beggar. Canter fits in row 6 with a couple of possible definitions in 3d and 21d and letters in 28a. That would mean an alternative clue is needed for the definition of grunt and one possibility is 23d.
That then leaves "start" which is an anagram of St Tar (or perhaps tar in the stone) and is just where you would expect to find it - at the start of the puzzle!