I don't think bhaji is correct - it's more of a vegetable side-dish, on the whole. Onion bhaji is a little like a cake, but not much.
Don't know what to suggest instead, though!
I thought 'vegetureen' looked odd, so I tried to think of alternatives. If the clue had been 'patty' or 'pattie', then Vegeburger would have been good! (And then you'd have had a 'b' for the cake clue!)
This is the Sun crossword and so it is not usually difficult but this clue has got us flummoxed.I wish I still had the paper to give you the crossing clues but I don't.