Note: tipsy gamers ruined computer software (9,6)
I believe the answer is:
operating system
'computer software' is the definition.
'note tipsy gamers ruined' is the wordplay.
'ruined' indicates anagramming the letters.
'note'+'tipsy'+'gamers'='notetipsygamers'
'notetipsygamers' anagrammed gives 'OPERATING SYSTEM'.
(Other definitions for operating system that I've seen before include "MO?" , "surgical procedure?" , "Essential software" , "Essential computer facility" , "Software providing a computer's basic functions" .)