'Glo', so to speak? (5)
I believe the answer is:
lingo
If this is the answer, I'm afraid I cannot explain it.
Can you help me to learn more?
(Other definitions for lingo that I've seen before include "Unfamiliar language or jargon" , "Language, colloquially speaking." , "Johnny Foreigner speaks one" , "Language (informally)" , "Tongue" .)