The British-born musician, who blended western and Zulu music, had been diagnosed with pancreatic cancer in 2015.
Known occasionally as the “white Zulu”, he was a vocal critic of South Africa’s apartheid government, with his best-known hit – 1987’s “Asimbonanga” ("We have not seen him") – one of the first to call for Nelson Mandela’s release.
Clegg, a white man who learnt to sing and speak in Zulu, broke the law to play with black musicians back in the era of racial apartheid and became a symbol of democratic South Africa.
At the time, much of his music was banned from the radio and his public performances were limited until the end of apartheid in 1994.
“We had to find our way around a myriad of laws that prevented us from mixing across racial lines,” he told AFP news agency in 2017.
Clegg’s long-time music manager, Ronny Quinn, who announced the news of his death, said Clegg left “deep footprints in the hearts of every person that considers himself or herself to be an African”.
“He showed us what it was to assimilate to and embrace other cultures without losing your identity,” he said.
The South African government is among the organisations, public figures and fans to pay tribute to Clegg.