The most common and most likely answer to this crossword clue is the 4 plus 3 plus 3 letter word LEAD THE WAY
I've seen this crossword clue in The Times
L
E
A
D
T
H
E
W
A
Y
Buddy explains!
The straight part
We know that "to act as guide" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case to act as guide = lead the way.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.