Great admirer of speech at wedding introducing former Republican (8)
I believe the answer is:
idolater
'great admirer' is the definition.
(I've seen this before)
'wedding introducing former republican' is the wordplay.
'wedding' becomes 'ido' (I am not sure about this - if you are sure you should believe this answer much more).
'introducing' means one lot of letters go next to another.
'former' becomes 'late' (late can mean former or previous).
'republican' becomes 'r' (abbreviation).
'ido'+'late'+'r'='IDOLATER'
'of speech at' acts as a link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for idolater that I've seen before include "Tailored like pagan worshipper" , "Strong admirer" , "Huge admirer" , "devoted fan" , "Tailored for image worshipper" .)