Shunned soldier turning up? No, communist (7)
I believe the answer is:
ignored
'shunned' is the definition.
(I've seen this before)
'soldier turning up? no communist' is the wordplay.
'soldier' becomes 'GI' (term for US soldier).
'turning up?' says the letters should be written backwards.
'communist' becomes 'red' (red can informally mean communist).
'gi' written backwards gives 'ig'.
'ig'+'no'+'red'='IGNORED'
(Other definitions for ignored that I've seen before include "Cut" , "Shunned" , "Took no notice of" , "Snubbed" , "cast aside" .)