OK, rip up my comic fast! (3,6)
I believe the answer is:
yom kippur
'fast' is the definition.
(I've seen this before)
'ok rip up my comic' is the wordplay.
'comic' indicates an anagram.
'ok'+'rip'+'up'+'my'='okripupmy'
'okripupmy' anagrammed gives 'YOM KIPPUR'.
(Other definitions for yom kippur that I've seen before include "Holiest fast day of the Jewish calendar" , "Religious fast" , "Jewish holy day" , "Jewish holiday, also called Day of Atonement" , "'Day of Atonement for Jews (3,6)'" .)