Welcome one version, English (3)
I believe the answer is:
ave
'welcome' is the definition.
('ave' is a Latin greeting)
'one version english' is the wordplay.
'one' becomes 'a' (a thing is one thing).
'version english' becomes 've' (this might be a standard abbreviation which I don't know about).
'a'+'ve'='AVE'
Can you help me to learn more?
(Other definitions for ave that I've seen before include "Hello to the old Romans" , "Hail (Latin)" , "Hail as to Caesar" , "Hail as to Maria" , "Latin greeting" .)