The maximum amount of rares you can get from a clue is 6. You get one "reward" per each clue part. So for level 3 clues you get a minimum of 4 rewards, maximum of 6. Level 2 is 3-5, level 1 is 2-4. It's possible to get 6 robins in a clue, just VERY VERY unlikely. Most rares I've personally gotten is 3, all rubbish ones too :( From my first few clues I had 5 rares. First one was Sara plate and legs, then Guthix kite and rune plate (t) then a pirate hat in the next clue. This was just after clues came out =P