Man addressed in stadium is terrific (6)
I believe the answer is:
mister
'man' is the definition.
(mister is a kind of man)
'in stadium is terrific' is the wordplay.
'in' says the answer is hidden in the clue.
'MISTER' is hidden in the letters of 'stadium is terrific'.
'addressed' is the link.
This may not be right. It may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for mister that I've seen before include "Merits of form of address to man" , "Bloke" , "that's what you'd call him" , "Form of address to a man, used without his name" , "Set rim (anag.)" .)