Cultivated a mowed field (6)
I believe the answer is:
meadow
'field' is the definition.
(a meadow is a field)
'cultivated a mowed' is the wordplay.
'cultivated' is an anagram indicator.
'a'+'mowed'='amowed'
'amowed' is an anagram of 'MEADOW'.
(Other definitions for meadow that I've seen before include "Pasture" , "somewhere grassy" , "Grassy field" , "it's green here" , "Hayfield" .)