I just hunted for the initial letter - and then spotted how to follow/get him. It's not in a straight line as such, but the letters are all in the correct order, in a logical path.
30a Stop vessel heading for Elat (4) O?O?
37a Arthur Miller's words about success (attributed) (6) D???O?
42a Learner getting into revision again (8) ?E?OL?E?