Absolutely ate dry crackers in the past (9)
I believe the answer is:
yesterday
'in the past' is the definition.
(I've seen this before)
'absolutely ate dry crackers' is the wordplay.
'absolutely' becomes 'yes' (I've seen this before).
'crackers' indicates an anagram (informal term for mad).
'ate'+'dry'='atedry'
'atedry' anagrammed gives 'terday'.
'yes'+'terday'='YESTERDAY'
(Other definitions for yesterday that I've seen before include "Song about break-up" , "Much-recorded song" , "Day before today" , "24 hours ago - hit for The Beatles" , "Twenty-four hours ago" .)