The most common and most likely answer to this crossword clue is the 12 letter word MICHELANGELO
I've seen this crossword clue in The Times
M
I
C
H
E
L
A
N
G
E
L
O
More clues leading to the result MICHELANGELO
- Artist and singer’s aid — he joins film director with band of the ’70s
- David was his second outstanding challenge, I suspect
- Confounding logical men, he becomes Renaissance figure
- Painter calling home, possibly about start of employment
- Artist calling home, ‘e became disorientated
- He painted chemical gel on building after crossing chimney’s top
- Old master in main college upset about husband
Buddy explains!
The straight part
We know that "Old master" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case old master = michelangelo.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.