Related Clues:

• Computerist
• Smoking or drinking, some say
• Frailty
• Habitual user
• End follower
• False friend
• PC person
• Dealer's customer
• One getting a manual
• Fiend … or a hint to this puzzle's theme
• Devotee, plus
• Product endorser, hopefully
• One with a password, perhaps
• One pushing a mouse around?
• Smoking, say