Car workers who succeeded on 'What's My Line? (5,7)
I believe the answer is:
panel beaters
'car workers' is the definition.
'succeeded on 'what's my line?' is the wordplay.
I cannot quite understand how this works, but
'succeeded' could be 's' (genealogical abbreviation) and 's' is present in the answer.
'on' could be 'at' (I've seen this in other clues) and 'at' is found in the answer.
'line?' could be 'el' (el is a kind of line) and 'el' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'who' is the link.
Can you help me to learn more?
(Another definition for panel beaters that I've seen is " Workers".)