All forex broker in singapore are follow under MAS regulation,they must become authorised by the Monetary Authority of Singapore (MAS), which is the financial regulatory body in Singapore. once the brokers have apply the operate licence, it will save to open a trading account with them, like IG group, Saxo Bank, City Index, Oanda, Plus500,CMC market...etc
You can safe open a live forex trading account if the broker have the MAS operate licence, my open with Oanda broker in singapore, you can choose whether open in USD or Sing Dollars trading account.