Dim female isn't slangy (5)
I believe the answer is:
faint
'dim' is the definition.
(I know that dim can be written as faint)
'female isn't slangy' is the wordplay.
I cannot quite see how this works, but
'female' could be 'fa' (I've seen this in other clues) and 'fa' is found within the answer.
The remaining letters 'int' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for faint that I've seen before include "Swoon; indistinct" , "dull" , "woozy" , "Barely perceptible" , "Swoon, lose consciousness" .)