Womaniser's reluctant air misled Olive at first (8)
I believe the answer is:
lothario
'womaniser's' is the definition.
(Lothario is an example)
'reluctant air misled olive at first' is the wordplay.
'reluctant' becomes 'loth' (if you are loth to do something you are reluctant).
'misled' is an anagram indicator (I've seen 'misleading' mean this (I've seen this in other clues)).
'at first' indicates taking the first letters.
The first letter of 'olive' is 'o'.
'air' anagrammed gives 'ari'.
'loth'+'ari'+'o'='LOTHARIO'
(Other definitions for lothario that I've seen before include "A Gay libertine" , "Successful womaniser" , "Libertine or woman-chaser" , "Casanova" , "Womanizser" .)