The most common and most likely answer to this crossword clue is the 7 letter word BYPATHS
I've seen this crossword clue in The Daily Telegraph
B
Y
P
A
T
H
S
Buddy explains!
The straight part
We know that "Sideways" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case sideways = bypaths.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 BYPATHS mean?
BYPATHS noun- An unfrequented path; an indirect route; a byway.