The most common and most likely answer to this crossword clue is the 7 letter word SLEDGER
I've seen this crossword clue in Financial Times
S
L
E
D
G
E
R
More clues leading to the result SLEDGER
Buddy explains!
The straight part
We know that "On field one might insult/winter traveller" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case on field one might insult/winter traveller = sledger.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.