The most common and most likely answer to this crossword clue is the 5 plus 2 plus 5 letter word RULES OF THUMB
I've seen this crossword clue in The Daily Telegraph
R
U
L
E
S
O
F
T
H
U
M
B
More clues leading to the result RULES OF THUMB
Buddy explains!
The straight part
We know that "Rough guides" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case rough guides = rules of thumb.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.