As eaten in Dad's Army? (5)
I believe the answer is:
pasta
'as eaten in' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'dad's army?' is the wordplay.
'dad's' becomes 'pa's' (both can mean one's father).
'army?' becomes 'TA' (abbreviation for Territorial Army).
'pas'+'ta'='PASTA'
Can you help me to learn more?
(Other definitions for pasta that I've seen before include "Dried flour paste used in cooking Italian dishes" , "Italian dough" , "Italian cooking staple" , "Eg, lasagne" , "Staple Italian food base" .)