Just one taking it the wrong way and expressing disgust would be all that we need (6)
I believe the answer is:
enough
'disgust would be all that we need' is the definition.
Although both the answer and definition are singular nouns, I don't see how they can define each other.
'just one taking it the wrong way and expressing' is the wordplay.
'just one' becomes 'one' (only one).
'taking it the wrong way' is a reversal indicator.
'and' is a charade indicator (letters next to each other).
'expressing' becomes 'ugh' (I can't explain this - if you can you should believe this answer much more).
'one' in reverse letter order is 'eno'.
'eno'+'ugh'='ENOUGH'
Can you help me to learn more?
(Other definitions for enough that I've seen before include "Adequate amount to meet the purpose" , "To the required degree" , "This'll do" , "This is going no further!" , "As many as necessary" .)