PM shown as pagan type when passing on measure (5)
I believe the answer is:
heath
'pm' is the definition.
(prime minister Edward Heath)
'pagan type when passing on measure' is the wordplay.
'pagan type' becomes 'heathen' (both can mean a non-Christian).
'when passing on' suggests deleting specific letters.
'measure' becomes 'en' (typographical measure).
'heathen' with 'en' taken out is 'HEATH'.
'shown as' is the link.
(Other definitions for heath that I've seen before include "Edward -, former PM" , "Area of common unproductive land" , "Moorland shrub" , "Moor" , "Open land with acid soil" .)