Teachers describing western uplands (5)
I believe the answer is:
downs
'uplands' is the definition.
(down is a kind of upland)
'teachers describing western' is the wordplay.
'teachers' becomes 'dons' (don is a kind of teacher).
'describing' is an insertion indicator (describe can mean to form the outline of).
'western' becomes 'w'.
'dons' going around 'w' is 'DOWNS'.
(Other definitions for downs that I've seen before include "Drinks in one" , "Southern uplands" , "Knocks over; drinks" , "North or South, two features of chalk upland in England" , "S. England chalk hills" .)