Working the land, up to a certain time in life (7)
I believe the answer is:
tillage
'working the land' is the definition.
(preparing land for growing crops)
'up to a certain time in life' is the wordplay.
'up to' becomes 'till' (up to or till a certain time).
'a certain time in life' becomes 'age'.
'till'+'age'='TILLAGE'
(Other definitions for tillage that I've seen before include "Cultivation of the soil" , "Work on land" , "Farming" , "Cultivation of fields" , "digging" .)