Setter's old, funny and latterly ignoring the odds getting extreme admiration (8)
I believe the answer is:
'extreme admiration' is the definition.
(I've seen this before)
'setter's old funny and latterly ignoring the odds' is the wordplay.
'setter' becomes 'i' (the person that set the crossword).
'funny' indicates an anagram.
'and' means one lot of letters go next to another.
'ignoring the odds' indicates alternate letters (letters in odd-numbered positions are removed).
The alternate letters of 'latterly' are 'atry'.
'old' with letters rearranged gives 'dol'.
'getting' is the link.
(Other definitions for idolatry that I've seen before include "reverence" , "Worship of a false god" , "Excessive adoration" , "Adroitly (anag.)" , "bowing down before a goddess?" .)