Cultivates grass in empty barns (6)
I believe the answer is:
breeds
'cultivates' is the definition.
The answer and definition can be both to do with creating things as well as being verbs in their -s form.
Maybe you can see an association between them that I can't see?
'grass in empty barns' is the wordplay.
'grass' becomes 'reed' (I've seen this before).
'in' means one lot of letters goes inside another.
'empty' suggests removing the centre.
'barns' with its middle removed is 'bs'.
'reed' placed inside 'bs' is 'BREEDS'.
Can you help me to learn more?
(Other definitions for breeds that I've seen before include "Produces offspring" , "Generates" .)