The most common and most likely answer to this crossword clue is the 11 letter word DEERSTALKER
I've seen this crossword clue in The Times
D
E
E
R
S
T
A
L
K
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R
More clues leading to the result DEERSTALKER
- Expensive-sounding Society speech-maker’s peaked cap
- Rare elks Ted shot, wearing this?
- Headgear for follower of game
- Sherlock’s covering case of evidence gathered by doctor, follower
- Hat comes from expensive-sounding shop in converted residence
- A top case for Sherlock Holmes?
- A red kestrel destroyed hat
- Hat of straw rejected by crazy follower
- Lester Drake adjusted hunter’s hat
Buddy explains!

The straight part
We know that "this?" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case this? = deerstalker.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 DEERSTALKER mean?
DEERSTALKER noun- One who takes part in deer stalking.
- A type of men's headwear, made of cloth with a plaid pattern, having two projecting brims (one at the front and one at the back) and earflaps which can be folded up and tied at the top.