One goes into it backwards (7)
I believe the answer is:
reverse
This might be a double definition.
'one' is the first definition.
Both the answer and definition are adjectives. Maybe there's an association between them I don't understand?
'it backwards' is the second definition.
The definition suggests a singular noun which matches the answer.
'goes into' acts as a link.
Can you help me to learn more?
(Other definitions for reverse that I've seen before include "Back (of a coin or medal)" , "Travel backwards" , "Turn inside out or upside down" , "One side of a coin" , "Transpose" .)