Loudly applauded old guerrilla, European socialist (7)
I believe the answer is:
cheered
'loudly applauded' is the definition.
'cheered' can be an answer for 'applauded' (cheering is a kind of applauding). I'm not sure about the 'loudly' bit.
'old guerrilla european socialist' is the wordplay.
'old guerrilla' becomes 'che' (guerrilla fighter Che Guevara. I am not sure about the 'old' bit.).
'european' becomes 'E' (abbreviation e.g. EU).
'socialist' becomes 'red' (red can informally mean a socialist).
'che'+'e'+'red'='CHEERED'
Can you help me to learn more?
(Other definitions for cheered that I've seen before include "Was happier" , "Comforted" , "Applauded and heartened" , "getting up, usually" .)