Constituent parts of cattle food (5,5)
I believe the answer is:
grass roots
'constituent parts of cattle food' is the definition.
I can't judge whether this defines the answer.
'constituent parts' is the wordplay.
I cannot really understand how this works, but
'parts' could be 'roots' (root is a kind of part) and 'roots' is present in the answer.
The remaining letters 'grass' is a valid word which might be clued in a way I don't see.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for grass roots that I've seen before include "ordinary folk" , "Most basic level" , "gardening issue?" , "Ordinary people (basis of lawn?)" , "Rank and file at the local level" .)