We hear group of countries support barrier (8)
I believe the answer is:
blockade
'barrier' is the definition.
(thesaurus)
'we hear group of countries support' is the wordplay.
'we hear' indicates a 'sounds like' (homophone) clue.
'group of countries' becomes 'bloc' (I've seen this before).
'support' becomes 'ade' (I can't justify this - if you can you should believe this answer much more).
'bloc' sounds like 'block'.
'block'+'ade'='BLOCKADE'
Can you help me to learn more?
(Other definitions for blockade that I've seen before include "Seal off (a sea port)" , "Action taken to prevent entry as of goods" , "Besiege" , "Prevent(ion of) access and exit" , "Isolation of place by sea" .)