Ration in the army? (7)
I believe the answer is:
serving
'the army?' is the definition.
Although both the answer and definition are singular nouns, I cannot see how one could define the other.
'ration in' is the wordplay.
I cannot really understand how this works, but
'in' is found in the answer.
This may be the basis of clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for serving that I've seen before include "Quantity of food for one person" , "Portion of food - being useful" .)