Clue: Manufacturer of pop, like one Jack drinks (5)
Answer: OASIS
Explanation: Definition: Manufacturer of pop
An envelope ('drinks') of AS ('like') plus I ('one', Roman numeral or personal pronoun) in OS (Ordinary Seaman, 'Jack'), for one of the pop music bands so named (but not the soft drink – it is a brand name of the drink, not its manufacturer, and 'pop' generally refers to something carbonated; thus the definition is cryptic).