Elected, Heath possibly supports enclosure (2-5)
I believe the answer is:
co-opted
'elected' is the definition.
(co-opting is a kind of electing)
'heath possibly supports enclosure' is the wordplay.
'heath possibly' becomes 'Ted' (former UK prime minister Ted Heath).
'supports' means one lot of letters go next to another (bottom letters provide a support for the top ones).
'enclosure' becomes 'coop' (coop is a kind of enclosure).
'ted' put after 'coop' is 'CO-OPTED'.
(Other definitions for co-opted that I've seen before include "Pressed (into service)" , "Added (to committee)" .)