The most common and most likely answer to this crossword clue is the 6 letter word TOPPER
I've seen this crossword clue in The Sunday Telegraph
T
O
P
P
E
R
More clues leading to the result TOPPER
Buddy explains!
The straight part
We know that "hat" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case hat = topper.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 TOPPER mean?
TOPPER noun- Something that is on top.
- A top hat.
- Something that exceeds those previous in a series, as a joke or prank.
- A short outer jacket worn by women or children.
- A soft, relatively thin, piece of padding placed on top of a mattress, or forming the upper layer of a mattress.
- The student who achieves the highest score in an examination.
- The head or chief of an organization.
- Something for cutting off the top of something.
- One who tops steel ingots.
- A single-handed dinghy, 11 foot (3.6 metres) in length, with only one sail.
- A three-square float, or file, used by comb-makers.
- Tobacco left in the bottom of a pipe bowl; so called from being often taken out and placed on top of the newly filled bowl.
- A fine or remarkable thing or person.
- A small secondary comic strip seen along with a larger Sunday strip, and usually by the same author.