Former PM in unproductive territory? (5)
I believe the answer is:
heath
I believe this clue is a double definition.
'former pm' is the first definition.
(prime minister Edward Heath)
'unproductive territory?' is the second definition.
(territory without much plant growth)
'in' is the link.
(Other definitions for heath that I've seen before include "part of Hampstead" , "Place of gorse/heather" , "Uncultivated land area" , "PM 1970-74" , "Sir Edward - , PM" .)