The most common and most likely answer to this crossword clue is the 6 letter word STRUTH
I've seen this crossword clue in Financial Times
S
T
R
U
T
H
More clues leading to the result STRUTH
Buddy explains!

The straight part
We know that "Gosh" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case gosh = struth.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 STRUTH mean?
STRUTH interjection- A mild oath expressing surprise or generally adding emphasis.