Mendicant would appear when this food produced in bar (3)
I believe the answer is:
egg
'mendicant would appear when this food produced in bar' is the definition.
'egg' can be an answer for 'food' (egg is a kind of food). I am not certain of the remainder of the definition.
'food produced in bar' is the wordplay.
'food' becomes 'e' (E is an example).
'produced in bar' becomes 'gg' (I can't justify this - if you can you should give a lot more credence to this answer).
'e'+'gg'='EGG'
Can you help me to learn more?
(Other definitions for egg that I've seen before include "Reproductive part" , "Source" , "Breakfast food, perhaps" , "Organism protected by shell" , "start in life" .)