The most common and most likely answer to this crossword clue is the 7 letter word ENDWISE
I've seen this crossword clue in The Daily Telegraph
E
N
D
W
I
S
E
Buddy explains!

The straight part
We know that "back to front" is the straight/definition part of the clue. The straight part is often a synonym or definition, in this case back to front = endwise.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 ENDWISE mean?
ENDWISE adjective- On-end; upright; pertaining or relating to the end.
- Upright, or standing on end
- With the end towards the front or towards the observer
- Towards the ends