You will need a liquor licence. This has to be approved by the police, but they are usually interested in where the liquor is to be warehoused.
You can look on Enterprise One website for advice on the permits.
http://www.business.gov.sg/
* Industries / Business Activities
Industries / Business Activities > Wholesale (Import, Export and Distribute) > Wholesale of Foodstuffs and Beverage > Wholesale of liquor and soft drinks >
That should give you a better idea of what you need.