Put off some food — consumed sandwiches last for dinner (10)
I believe the answer is:
dishearten
'put off' is the definition.
(I know that put off can be written as dishearten)
'some food consumed sandwiches last for dinner' is the wordplay.
'some food' becomes 'dish' (dish is a kind of food).
'consumed' becomes 'eaten' (similar in meaning).
'sandwiches' means one lot of letters goes inside another (to sandwich is to block something in).
'last for' says to take the final letters.
The final letter of 'dinner' is 'r'.
'eaten' going around 'r' is 'earten'.
'dish'+'earten'='DISHEARTEN'
(Other definitions for dishearten that I've seen before include "Take away bottle" , "Cause (someone) to lose confidence" , "Bring down" , "dismay?" , "Put a damper on" .)