Diaries occasionally displaying anger (3)
I believe the answer is:
ire
'anger' is the definition.
(I've seen this before)
'diaries occasionally' is the wordplay.
'occasionally' indicates alternate letters.
The alternate letters of 'diaries' are 'IRE'.
'displaying' is the link.
(Other definitions for ire that I've seen before include "Losing head" , "Hot temper" , "passionate feeling" , "Irritation, anger" , "Displeasure" .)