Ptomaine could come from beef producer in can (5)
I believe the answer is:
toxin
'ptomaine could come' is the definition.
I can't tell whether this defines the answer.
'from beef producer in can' is the wordplay.
'from' becomes 'o' (I've seen this in other clues).
'beef producer' becomes 'x' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'in' is an insertion indicator.
'can' becomes 'tin' (both are metal containers).
'o'+'x'='ox'
'ox' put into 'tin' is 'TOXIN'.
Can you help me to learn more?
(Other definitions for toxin that I've seen before include "Poison of organic origin" , "Form of poison" , "Poisonous substance" , "Poison, venom" , "Natural poison" .)