Mayonnaise sent back contains bug (5)
I believe the answer is:
annoy
'bug' is the definition.
(thesaurus)
'mayonnaise sent back contains' is the wordplay.
'contains' says the answer is hidden in the clue.
'sent back' shows that the letters should be reversed in order.
'yonna' is hidden within 'mayonnaise'.
'yonna' in reverse letter order is 'ANNOY'.
(Other definitions for annoy that I've seen before include "Exasperate" , "Irritate, nettle" , "Irk" , "Upset" , "trouble" .)