Ravenous Shakers ate sandwiches (8)
I believe the answer is:
famished
'ravenous' is the definition.
(synonyms)
'shakers ate sandwiches' is the wordplay.
'shakers' becomes 'amish' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'ate' becomes 'fed' ('feed' can be a synonym of 'eat').
'sandwiches' means one lot of letters goes inside another (inserted letters are sandwiched in).
'amish' put inside 'fed' is 'FAMISHED'.
Can you help me to learn more?
(Other definitions for famished that I've seen before include "Is fed ham, being very hungry" , "Extremely hungry" , "Ma fished, being starved" .)