Poor Annie's crazy (6)
I believe the answer is:
'crazy' is the definition.
(I know that crazy can be written as insane)
'poor annie's' is the wordplay.
'poor' is an anagram indicator.
'annies' is an anagram of 'INSANE'.
(Other definitions for insane that I've seen before include "out to lunch" , "Mentally unhinged" , "Anne is (anag) - crazy" , "mad for love?" , "Deranged, crazy" .)