Starts for Riga from Singapore (5)
I believe the answer is:
opens
'starts' is the definition.
(opening is a kind of starting)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for opens that I've seen before include "Unseals" , "sports competitions" , "Tournaments for both professionals and amateurs" , "Removes a lid, say" , "Exposes, begins" .)