Crazy bird (6)
This clue is a double definition.
'crazy' is the first definition.
(I've seen this before)
'bird' is the second definition.
(I know that cuckoo is a type of bird)
(Other definitions for cuckoo that I've seen before include "Bird with a two-note call" , "Bananas" , "It takes over other birds' nests" , "It lays eggs in another's 15 across" , "Slightly crazy -- bird" .)
<span class="explanation-format__ClueExplanation">'<span class="explanation-format__original">crazy bird</span>' is the definition.<br/ ><span class="explanation-format__explanation">(I've seen this in another clue)</span><br/ ><br/ >This is all the clue.<br/ ></span>
(Other definitions for loon that I've seen before include "Fool" , "Simple-minded person" , "US bird is also a silly person?" , "N American diving bird" , "Diver; silly person" .)