The most common and most likely answer to this crossword clue is the 6 letter word INCHED
I've seen this crossword clue in Financial Times
I
N
C
H
E
D
Buddy explains!
The straight part
We know that "proceeded with caution" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case proceeded with caution = inched.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 INCHED mean?
INCHED verb- (followed by a preposition) To advance very slowly, or by a small amount (in a particular direction).
- To drive by inches, or small degrees.
- To deal out by inches; to give sparingly.
- (in combination) Being a certain number of inches in length.