Alien female’s solvent (5)
I believe the answer is:
ether
'solvent' is the definition.
(I've seen this in another clue)
'alien female's' is the wordplay.
'alien' becomes 'et' (extra terrestrial).
'female' becomes 'her' (I've seen this before).
'et'+'her'='ETHER'
(Other definitions for ether that I've seen before include "Imaginary interstellar medium" , "An early anaesthetic" , "Type of chemical" , "Former anaesthetic" , "Volatile solvent" .)