Chaotic form disowned, happy to come first (6,4)
I believe the answer is:
upside down
'chaotic' is the definition.
(thesaurus)
'form disowned happy to come first' is the wordplay.
'form' indicates anagramming the letters.
'happy' becomes 'up' (I've seen this in other clues).
'to come first' is a charade indicator (letters next to each other).
'disowned' anagrammed gives 'sidedown'.
'sidedown' put after 'up' is 'UPSIDE-DOWN'.
(Other definitions for upside down that I've seen before include "at sixes and sevens" , "Turned over" , "in disarray" , "The wrong way up" , "in a crazy way" .)