Muppet who says "balsamic vinegar" is a big word for him (4)
I believe the answer is:
elmo
(Other definitions for elmo that I've seen before include "Puppet character" , "St ...'s fire, weather phenomenon of coloured glow" , "Saint whose "fire" occurs around masts etc" , "Saint whose fire is electric!" , "Sesame Street character - patron saint of sailors (with his own fire)" .)