The most common and most likely answer to this crossword clue is the 7 letter word L-PLATE
I've seen this crossword clue in Financial Times
L
-
P
L
A
T
E
Buddy explains!
The straight part
We know that "Not according to this" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case not according to this = l-plate.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.