Among other things at airline mishandled (5,4)
I believe the answer is:
inter alia
'among other things' is the definition.
(synonyms)
'at airline mishandled' is the wordplay.
'mishandled' indicates an anagram.
'at'+'airline'='atairline'
'atairline' is an anagram of 'INTER ALIA'.
(Other definitions for inter alia that I've seen before include "Midst other things" , "among others" , "Among other things, in Latin" , "amongst others" , "amongst other things" .)