Question:  Let's Rock Again! is a music documentary film following a singer that was the lead vocalist of what punk band?
Sentence (from "Joe Strummer"): John Graham Mellor (21 August 1952 – 22 December 2002), known by his stage name Joe Strummer, was an English musician, singer, actor and songwriter who was the co-founder, lyricist, rhythm guitarist and lead vocalist of the Clash, a punk rock band formed in 1976 as part of the original wave of British punk.
Relevant evidence: Yes