Cut grass contains what cow chews up (7)
I believe the answer is:
reduced
'cut' is the definition.
(similar in meaning)
'grass contains what cow chews up' is the wordplay.
'grass' becomes 'reed' (type of grass plant).
'contains' is an insertion indicator.
'what cow chews' becomes 'cud' (cud is regurgitated food chewed by cows).
'up' says the letters should be written backwards (in down clue: letters go upwards).
'cud' backwards is 'duc'.
'reed' enclosing 'duc' is 'REDUCED'.
(Other definitions for reduced that I've seen before include "Lessened" , "Made smaller" , "Impoverished" , "Diminished - cut-price" , "Made less in size etc" .)