Base a lady's face on Hindu goddess (6)
I believe the answer is:
'base' is the definition.
(I know that base can be written as alkali)
'a lady's face on hindu goddess' is the wordplay.
'face' says to take the initial letters.
'on' is a charade indicator (letters next to each other).
'hindu goddess' becomes 'kali' (I've seen this in another clue).
The initial letter of 'lady' is 'l'.
(Other definitions for alkali that I've seen before include "Acid-neutralising substance" , "Acid neutraliser" , "Soluble compound that turns litmus paper blue" , "Chemical base" , "base solution" .)