Corrupt in very backway way (5)
I believe the answer is:
venal
'corrupt' is the definition.
(similar in meaning)
'in very backway way' is the wordplay.
'in' is an insertion indicator.
'very' becomes 'v' (abbreviation).
'backway' becomes 'eal' (I can't explain this - if you can you should believe this answer much more).
'way' becomes 'n' (Compass direction - North).
'v'+'eal'='veal'
'veal' placed around 'n' is 'VENAL'.
Can you help me to learn more?
(Other definitions for venal that I've seen before include "motivated by corruption" , "easily bribed" , "Susceptible to bribery" , "Corrupt, dishonest" , "can be bought cheaply" .)