Idol ran off first, say (7)
I believe the answer is:
ordinal
'first say' is the definition.
('first' is an ordinal number)
'idol ran off' is the wordplay.
'off' indicates anagramming the letters.
'idol'+'ran'='idolran'
'idolran' is an anagram of 'ORDINAL'.
(Other definitions for ordinal that I've seen before include "(Of numbers) first or second, perhaps" , "Old Iran (anag)" , "Roman Catholic service book" , "RC Church service book" , "Maybe first" .)