I do not think the answer to 4D - which is not a 'clashing clue' - matches its definition, in that to do so the fourth letter (which is checked by 15A, another non-clasher) would have to be 'a', not 'e'?
I agree about 4 down which clashes with 19 across and cannot find the spelling given by the word play anywhere. Kt17 - alpha, bravo, Charlie etc should help with the ambiguity.
Thanks alwayspuzzled - Yes I finished the grid and have all the corrected solutions, but it says "possible ambiguity in one case"
I guess it might be where 4D checks with 19A as either clashing letter would leave acceptable words, so Tigga is pointing us to enter a 'M' rather than a 'D'.
Surely 4 down is simply wrong. The xxxim answer is not fish - there is no alternative spelling in any dictionary I have checked of the fish xxeam. Otherwise a nice puzzle.