Cat's remark about trouble in field (6)
I believe the answer is:
meadow
'field' is the definition.
(a meadow is a field)
'cat's remark about trouble' is the wordplay.
'cat's remark' becomes 'mew' (I am not sure about this - if you are sure you should believe this answer much more).
'about' means one lot of letters goes inside another.
'trouble' becomes 'ado' (both can mean bother or commotion).
'mew' enclosing 'ado' is 'MEADOW'.
'in' is the link.
Can you help me to learn more?
(Other definitions for meadow that I've seen before include "area of grassland" , "Tract of cultivated grassland" , "Paddock" , "Piece of grassland" , "Field used for hay" .)