The most common and most likely answer to this crossword clue is the 6 letter word HOODIE
I've seen this crossword clue in Independent
H
O
O
D
I
E
More clues leading to the result HOODIE
Buddy explains!

The straight part
We know that "Top" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case top = hoodie.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 HOODIE mean?
HOODIE noun- A sweatshirt, with an integral hood and, sometimes, a large kangaroo pocket at the front.
- (often with negative connotation of yobbishness) A young person wearing such a sweatshirt, usually a male.
- Foreskin
- Hooded crow, Corvus cornix