Lean feast alternatives cost nothing (3-4)
I believe the answer is:
fat-free
'lean' is the definition.
(I've seen this before)
'feast alternatives cost nothing' is the wordplay.
I cannot quite see how this works, but
'nothing' could be 'fa' (slang term - sweet Fanny Adams) and 'fa' is located in the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for fat-free that I've seen before include "Skimmed" , "Like some restricted diets" , "Very low in saturates/unsaturates" , "Containing no greasy substances" , "Lite" .)