Mare chewed though grass courses of ample size (6,4)
I believe the answer is:
square meal
'courses of ample size' is the definition.
'square meal' can be an answer for 'courses' (I've seen this before). I'm not certain of the 'of ample size' bit.
'mare chewed though grass' is the wordplay.
I cannot really understand how this works, but
an anagram of 'mare' is 'arem' which is present in the answer.
The remaining letters 'squeal' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for square meal that I've seen before include "apparently not a round of sandwiches?" , "Substantial repast" , "Courses" , "proper food" , "Satisfying food" .)