R. Kelly Should 'Admit' He's a Pedophile, Says Father of Alleged Sex Slave

R. Kelly's new song fell way short of living up to its name, because he didn't admit he's a pedophile and a deadbeat dad ... so says the father of one of his alleged sex slaves.

Angelo Clary -- father of Azriel Clary -- tells TMZ ... Kelly took advantage of his daughter at the age of 17, which is a year too early under Florida law.

Clary insists R. Kelly is a pedophile, and says his "I Admit" lyrics about sympathizing with parents of his "girlfriends" are total BS.

As we reported ... Kelly addresses some of the sex cult allegations in the new, 19-minute long track -- in addition to his financial problems and celeb beefs with Steve Harvey and John Legend.

Clary doesn't give a damn about the singer's woes, but does suggest there's an easy fix for Kelly ... if he's really game.