One of the Muppets (4)
I believe the answer is:
elmo
'one of the muppets' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for elmo that I've seen before include "Saint whose fire is electric!" , "St ...'s fire, weather phenomenon of coloured glow" , "St ----'s Fire: aura from electrical discharge" , "Fiery saint" , "Saint associated with fire" .)