Private planes or otherwise (8)
I believe the answer is:
personal
'private' is the definition.
('personal' is associated in meaning with 'private')
'planes or otherwise' is the wordplay.
'otherwise' indicates an anagram.
'planes'+'or'='planesor'
'planesor' with letters rearranged gives 'PERSONAL'.
(Other definitions for personal that I've seen before include "Concerning the self" , "Wounding" , "Private - bodily" , "Affecting an individual" , "Relating to the individual" .)