Egg on vomit - eat accidentally! (8)
I believe the answer is:
motivate
'egg on' is the definition.
(thesaurus)
'vomit eat accidentally' is the wordplay.
'accidentally' is an anagram indicator (a chaotic or accidental ordering of the letters).
'vomit'+'eat'='vomiteat'
'vomiteat' anagrammed gives 'MOTIVATE'.
(Other definitions for motivate that I've seen before include "Stimulate the interest of" , "Induce" , "Give an incentive for action" , "Stimulate to action" , "Drive on" .)