Beneficial though self-contradictory in parts (9)
I believe the answer is:
wholesome
'beneficial' is the definition.
(I've seen this before)
'self-contradictory in parts' is the wordplay.
I cannot quite see how this works, but
'parts' could be 'holes' (hole is a kind of part) and 'holes' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'though' is the link.
Can you help me to learn more?
(Other definitions for wholesome that I've seen before include "Respectable" , "Previously propitious" , "Beneficial" , "Healthy in body, taste or morals" , "Good for you!" .)