A good appeal: support promotion of communism (8)
I believe the answer is:
agitprop
'promotion of communism' is the definition.
(agitprop means communist propaganda)
'a good appeal support' is the wordplay.
'good' becomes 'g' (abbreviation).
'appeal' becomes 'it' ('it' can mean something attractive or appealing).
'support' becomes 'prop' (prop up can mean to support).
'a'+'g'+'it'+'prop'='AGITPROP'
(Other definitions for agitprop that I've seen before include "Would rat go pip badly for the propagandist?" , "Culturally delivered political propaganda -- a top grip (anag)" , "left-wing literature" , "'Political agitation and propaganda, in short (8)'" , "Misleading info" .)