Dilapidated gate outside poorly cultivated land (7)
I believe the answer is:
tillage
'cultivated land' is the definition.
(synonyms)
'dilapidated gate outside poorly' is the wordplay.
'dilapidated' is an anagram indicator.
'outside' indicates putting letters inside.
'poorly' becomes 'ill' (synonyms).
'gate' is an anagram of 'tage'.
'tage' enclosing 'ill' is 'TILLAGE'.
(Other definitions for tillage that I've seen before include "Cultivation of crops" , "Land preparation" , "Cultivation of the land" , "Arable land worked by ploughing" , "Cultivation of the soil" .)