Leave before taking in rector's formal garden (8)
I believe the answer is:
parterre
'formal garden' is the definition.
(I've seen this before)
'leave before taking in rector's' is the wordplay.
'leave' becomes 'part' (parting is a kind of leaving**).
'before' becomes 'ere' (usually literary).
'taking in' indicates putting letters inside.
'rector' becomes 'r'.
'ere' going around 'r' is 'erre'.
'part'+'erre'='PARTERRE'
(Other definitions for parterre that I've seen before include "Part of the main floor of a theatre" , "Formal area of garden" , "flower-beds" , "Part of the main floor of a threatre" , "Seating on the ground floor of US theatre?" .)