1 down (4) ?I?D Some musicians take course that`s not straightforward? Doesn`t sound like it. 5 down (8) ?I?D?O?? Way to claim territory perhaps, for a lark. 19 across (4) ??T? It`s used in leaving a terminal.
I should have shown a little patience - many thanks to Tilly2 and geo0939. All three of you were faster on the draw than dannyk13 - a major achievement - perhaps he`s having a well-deserved lie-in this morning.