Missing person a bee sent crazy (8)
I believe the answer is:
absentee
'missing person' is the definition.
(I've seen this before)
'a bee sent crazy' is the wordplay.
'crazy' indicates anagramming the letters.
'bee'+'sent'='beesent'
'beesent' with letters rearranged gives 'bsentee'.
'a'+'bsentee'='ABSENTEE'
(Other definitions for absentee that I've seen before include "One away from work, etc" , "Missing person" , "shirker?" , "One who should be but isn't present" , "He's not here!" .)