Some ground needing bit of aftercare in retreat (4)
I believe the answer is:
acre
'some ground' is the definition.
(acre is a measure of land)
'bit of aftercare in retreat' is the wordplay.
'bit of' indicates the answer is hidden within the clue.
'in retreat' says the letters should be written in reverse.
'erca' is hidden within 'aftercare'.
'erca' back-to-front is 'ACRE'.
'needing' acts as a link.
(Other definitions for acre that I've seen before include "Middle East port" , "Care about the land measure" , "Care about the piece of land" , "0.405 of a hectare" , "Unit of area - Israeli port" .)