The most common and most likely answer to this crossword clue is the 4 plus 4 letter word POLO NECK
I've seen this crossword clue in The Guardian
P
O
L
O
N
E
C
K
More clues leading to the result POLO NECK
- Mint drink is top
- A warmer kiss and cuddle that holds up the game?
- Jumper in equestrian sport with narrow margin of victory
- Top down on Volkswagen
- Collar has solitary mark on the outside
- Single occupying spot in Jersey
- Star Trek character heading off to obtain separate clothing — like this?
- Top down, German car leading
- Small marks covering single items of clothing
- Sweet kiss, warmer?
Buddy explains!

The straight part
We know that "A warmer" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case a warmer = polo neck.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 POLO NECK mean?
POLO NECK noun- A high collar covering the neck; a turtleneck.
- A light type of shirt with such a collar; a turtleneck.