The most common and most likely answer to this crossword clue is the 4 letter word EARL
I've seen this crossword clue in Independent
E
A
R
L
More clues leading to the result EARL
- Peer in organ loft, but not very many times
- Top lady entertaining a large peer
- Mostly ancient member of a noble line
- Nobleman almost skinned!
- Nobleman covered in pearls
- Peer demanding attention last of all
- Nobleman ahead of schedule for the most part
- Gem’s not the first for noble
- Noble Shakespearean king, left from start to finish
- Arriving in good time – not quite 12?
Buddy explains!

The straight part
We know that "nobleman" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case nobleman = earl.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.
What does EARL mean?
EARL noun- (nobility) A British or Irish nobleman next in rank above a viscount and below a marquess; equivalent to a European count. A female using the style is termed a countess.
- Any of various nymphalid butterflies of the genus Tanaecia. Other butterflies in this genus are called counts and viscounts.