Being high, high up, I hear, without oxygen (8)
I believe the answer is:
euphoria
'being high' is the definition.
(I've seen this in another clue)
'high up i hear without oxygen' is the wordplay.
'high' indicates an anagram (can mean drunk or on drugs and hence disordered).
'without' indicates putting letters inside ('without' can be similar in meaning to 'outside').
'oxygen' becomes 'O' (atomic symbol for oxygen).
'up'+'i'+'hear'='upihear'
'upihear' with letters rearranged gives 'euphria'.
'euphria' going around 'o' is 'EUPHORIA'.
(Other definitions for euphoria that I've seen before include "Intense happy feeling" , "Ecstatic feeling" , "Intense feeling of well-being and excitement" , "Feeling of extreme elation" , "Great happiness and exhilaration" .)