Film about female amphibian (3)
I believe the answer is:
eft
'amphibian' is the definition.
(I know that eft is a type of Newt)
'film about female' is the wordplay.
'film' becomes 'ET' (E.T. the Extra-Terrestrial).
'about' means one lot of letters goes inside another.
'female' becomes 'f' (abbreviation).
'et' enclosing 'f' is 'EFT'.
(Other definitions for eft that I've seen before include "Small amphibian" , "Little creature" , "Juvenile twenty-three Ac; rhymes with sinister" , "Slimy creature" , "Young newt" .)