The most common and most likely answer to this crossword clue is the 5 plus 5 letter word MARIO LANZA
I've seen this crossword clue in Financial Times
M
A
R
I
O
L
A
N
Z
A
More clues leading to the result MARIO LANZA
Buddy explains!
The straight part
We know that "a tenner as advertised on the radio" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a tenner as advertised on the radio = mario lanza.The cryptic/wordplay part
In cryptic crossword there's often an wordplay/cryptic part as well.This part involves a more complex hint, such as an anagram, homophone, hidden word, etc.
Sadly, We don't have an explanation for this specific crossword clue yet.