Swear nothing is omitted from part of meal (5)
I believe the answer is:
curse
'swear' is the definition.
(synonyms)
'nothing is omitted from part of meal' is the wordplay.
'nothing' becomes 'o' (looks like zero - 0).
'is omitted from' suggests deleting specific letters.
'part of meal' becomes 'course' ('course' is part of 'meal').
'course' with 'o' removed is 'CURSE'.
(Other definitions for curse that I've seen before include "Execrate" , "Execration" , "Profanity" , "Cause of harm or misery" , "Swear - oath" .)