Caught in endless dishonest dealing (6)
I believe the answer is:
nailed
'caught' is the definition.
(I've seen this in another clue)
'endless dishonest dealing' is the wordplay.
'endless' means to look at the middle letters.
'dishonest' becomes 'venal' (synonyms).
'dealing' becomes 'ailed' (I can't justify this - if you can you should give a lot more credence to this answer).
The centre of 'venal' is 'n'.
'n'+'ailed'='NAILED'
'in' acts as a link.
Can you help me to learn more?
(Other definitions for nailed that I've seen before include "Exposed" , "not allowed to escape?" , "Properly fixed" , "Fixed; lead in (anag.)" , "Fixed - caught" .)