Rainbow Quiz - Identify the personality - Week 50

Here is the next weekly "Rainbow" quiz , where I would be giving 7 clues (Hence the name Rainbow) about a personality. Try to discover the person in the least number of clues . You can either leave the answer as a comment / email me . Feedback/ suggestions welcome. Googling is not preferred but then its just for fun and so go ahead if you need to.

This is a commemorative 50th week of Rainbow Quiz ! I will say very less about him here lest I give away the answer ! I am a huge fan of this eccentric genius. One of the most brilliant and effortless singers.Not a day goes by when I don't hear his voice .

clue # 1 : "X" was born as Abhas Kumar Ganguli, in a Bengali family.He was the youngest of four siblings.

clue # 2 : His brother became a famous Bollywood star. "X" used to visit him in Mumbai and started his cinema career as a chorus singer at Bombay Talkies. He did not have a formal training in music and initially used to imitate his idol - K.L.Saigal.

clue # 3 : Music director Khemchand Prakash gave him a chance to sing the song for the film Ziddi in the late 40's. Strangely he never made a great impact as a singer in the next two decades.

clue # 4 : He was not interested in acting, but was too afraid to rebel against his brother, who wanted him to be an actor like himself.After some initial flops as an actor, "X" achieved success as a comic hero in movies.

clue # 5 : Sachin Dev Burman , the famous music director, recognized the versatile singer hidden inside "X" and started grooming him. SDB's film Aradhana proved to be a turning point for "X" and there was no looking back after that . "X" became the voice of the nation and sang for all leading heroes and music directors in the 70's and 80's.

clue # 6 : He led an eccentric personal life. He was married four times to some of the most beautiful women. "X" is said to have been paranoid about not being paid.He also put a "Beware of X" sign at the door of his Warden Road flat.

clue # 7 : His versatility and contribution to Indian films is immeasurable. He was a playback singer,comic actor, lyricist, composer, producer, director, and scriptwriter.

Easy one. Who is X?