Female in fix over first of losses (4)
I believe the answer is:
girl
'female' is the definition.
(girl is a kind of female)
'fix over first of losses' is the wordplay.
'fix' becomes 'rig' (rig can mean to fix or manipulate).
'over' says the letters should be written in reverse.
'first of losses' becomes 'l' (1st letter of 'losses').
'rig' reversed gives 'gir'.
'gir'+'l'='GIRL'
'in' acts as a link.
(Other definitions for girl that I've seen before include "Maid" , "Lass" , "Young woman" , "See 5" , "A young female" .)