The most common and most likely answer to this crossword clue is the 7 letter word BOBSLED
I've seen this crossword clue in The Times
B
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More clues leading to the result BOBSLED
Buddy explains!

The straight part
We know that "form of winter sport" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case form of winter sport = bobsled.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 BOBSLED mean?
BOBSLED noun- A sled used to go down a bob track.
- The sport of travelling down a bob track as fast as possible.
- A short sled, mostly used as one of a pair connected by a reach or coupling; the compound sled so formed.
- To ride a bobsled.