Scrawny person might get one from butcher for pet? (3,2,5)
I believe the answer is:
bag of bones
'scrawny person' is the definition.
I don't know anything about this answer so I cannot tell whether this works.
'get one from butcher for pet?' is the wordplay.
'get' becomes 'bag' (bag can mean to secure or obtain).
'one from' becomes 'of' (of can mean from or belonging to).
'butcher for pet?' becomes 'bones' (I can't justify this - if you can you should believe this answer much more).
'bag'+'of'+'bones'='BAG OF BONES'
'might' acts as a link.
Can you help me to learn more?
(Other definitions for bag of bones that I've seen before include "Extremely thin person" , "case for doctor?" .)