25d one may be set on repeatedly ? one must hide (5) O-I-N This could be Onion (on repeated) with i (one hidden ) but I don't undertand .. the rest of the clue 'one may be set'. ?
Or this could be Orion - the hunter who set on his prey who needed to hide ?
I prefer the fromer answer but would like a better explantion as the why the answer is what it is ?