The most common and most likely answer to this crossword clue is the 7 letter word IMPALED
I've seen this crossword clue in The Daily Telegraph
I
M
P
A
L
E
D
More clues leading to the result IMPALED
Buddy explains!

The straight part
We know that "transfixed" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case transfixed = impaled.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 IMPALED mean?
IMPALED verb- To pierce (something) with any long, pointed object.
- To place two coats of arms side by side on the same shield (often those of two spouses upon marriage).
- To pierce with a pale; to put to death by fixing on a sharp stake.
- To enclose or fence with stakes.
- Pinned to something by piercing.