Cut grass hides bird without tail (7)
I believe the answer is:
reduced
'cut grass hides bird without tail' is the definition.
I can't judge whether this definition defines the answer.
'cut grass hides bird without tail' is the wordplay.
'cut grass' becomes 'reed' (I can't justify this - if you can you should give a lot more credence to this answer).
'hides' means one lot of letters goes inside another.
'bird' becomes 'duck' (duck is a kind of bird).
'without tail' means to remove the last letter.
'duck' with its last letter removed is 'duc'.
'reed' going around 'duc' is 'REDUCED'.
Can you help me to learn more?
(Other definitions for reduced that I've seen before include "looked smaller" , "Shortened" , "Boiled down" , "Made less in size etc" , "Impoverished" .)