Not available in the shops if derived from farm animals (3,2,5)
I believe the answer is:
out of stock
'not available in the shops if derived' is the definition.
I can't tell whether this defines the answer.
'from farm animals' is the wordplay.
'from' becomes 'out of' (I've seen this in another clue).
'farm animals' becomes 'stock' (I've seen this before).
'outof'+'stock'='OUT-OF-STOCK'
Can you help me to learn more?
(Other definitions for out of stock that I've seen before include "Not available, all sold" , "unavailable?" , "Not available for sale" , "Thus soup might be made" .)