Last song about social policy (8)
I believe the answer is:
glasnost
'social policy' is the definition.
(I know that glasnost is a type of social policy)
'last song about' is the wordplay.
'about' indicates an anagram.
'last'+'song'='lastsong'
'lastsong' is an anagram of 'GLASNOST'.
(Other definitions for glasnost that I've seen before include "Policy of openness under Gorbachev" , "Soviet policy of openness" , "Gorbachev's policy from 1985" , "Openness (Russian)" , "Gorbachev's policy of "openness"" .)