Giggly Muppet (4)
I believe the answer is:
elmo
'giggly muppet' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for elmo that I've seen before include "St ...'s fire, weather phenomenon of coloured glow" , "St ----'s Fire: aura from electrical discharge" , "Saint whose fire is electric!" , "Fiery saint" , "Saint whose "fire" occurs around masts etc" .)