Lover to ace airman marshalled ... (9)
I believe the answer is:
inamorata
'lover' is the definition.
(I've seen this in another clue)
'to ace airman marshalled' is the wordplay.
'ace' becomes 'a' (abbreviation).
'marshalled' indicates anagramming the letters (I've seen 'marshals' mean this (marshal can mean to gather)).
'to'+'a'+'airman'='toaairman'
'toaairman' anagrammed gives 'INAMORATA'.
(Other definitions for inamorata that I've seen before include "Woman beloved" , "Someone fancies her" , "Girlfriend" , "loved one" , "Sweetheart" .)