Complex sentence: Hrithik Roshan, who grew up to become one of India's most acclaimed superstar actors, but was in 1980 just a tiny child aged 6--danced spontaneously while visiting Grandpa's set during a song sequence.
Split into simpler sentences: Hrithik Roshan, who grew up to become one of India's most acclaimed superstar actors. In 1980 he was a child age 6 who danced spontaneously while visiting grandpa's set during a song sequence.