Planted one's plant well (12)
I believe the answer is:
satisfactory
'well' is the definition.
(similar in meaning)
'planted one's plant' is the wordplay.
'planted' becomes 'sat' (planted can mean sat in a particular place).
'one's' becomes 'I's' (Roman numeral).
'plant' becomes 'factory'.
'sat'+'is'+'factory'='SATISFACTORY'
(Other definitions for satisfactory that I've seen before include "unexceptional" , "Fully acceptable" , "fine" , "Meeting expectations" , "Acceptable - adequate" .)