Failure to appear (7)
I believe the answer is:
absence
'failure to appear' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for absence that I've seen before include "form of inattention?" , "It may make the heart grow fonder" , "Failure to attend" , "Seen cab (anag.)" , "Want (of something)" .)