Nose absorbs source of meat substitute (5)
I believe the answer is:
proxy
'substitute' is the definition.
(thesaurus)
'nose absorbs source of meat' is the wordplay.
'nose' becomes 'pry' ('pry' can be a synonym of 'nose').
'absorbs' indicates putting letters inside.
'source of meat' becomes 'ox' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'pry' going around 'ox' is 'PROXY'.
Can you help me to learn more?
(Other definitions for proxy that I've seen before include "Authorised substitute" , "Authority to represent others" , "Agent (for eg voting)" , "Person authorised to act on behalf of another" , "Stand-in, agent" .)