As a detective tasked with solving the mystery of the crossword clue ‘Telly on the telly, once‘, my first thought was to understand the context of the clue. Since ‘Telly‘ is a colloquialism for television shows, I started to think of actors who were famous for their roles in TV shows. Next, I tried to look for common letters in the clue that would help me narrow down my search. The word ‘telly‘ appeared twice, which made me focus on actors who had a distinctive association with the medium of television. As I was pondering on various names, I suddenly remembered Kojak, the detective character played by Telly Savalas in the eponymous TV show. The character and the actor have become synonymous with each other, and many people refer to Telly Savalas as just ‘Telly‘. Thus, my thought process led me to the conclusion that ‘Telly on the telly, once‘ was a reference to Telly Savalas’ portrayal of Kojak on television, making ‘SAVALAS‘ the answer to the crossword puzzle.