Greeting triumphant expression while keeping watch (5)
I believe the answer is:
aloha
'greeting' is the definition.
(I've seen this before)
'triumphant expression while keeping watch' is the wordplay.
I cannot quite understand how this works, but
'watch' could be 'lo' (archaic exclamation meaning 'look!') and 'lo' is found in the answer.
'expression' could be 'aha' (I have seen 'Expression of surprise ' mean 'aha' so perhaps 'expression' could also mean 'aha') and 'aha' is present in the leftover letters.
No letters remain.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for aloha that I've seen before include "greeting in Oahu" , "Hawaiian farewell" , "Hawaiian hello or goodbye" , "Welcome to Honolulu!" , "Hi! in Honolulu" .)