Out-and-out lies oddly cause resentment (6)
I believe the answer is:
rankle
'cause resentment' is the definition.
(I've seen this before)
'out-and-out lies oddly' is the wordplay.
'out-and-out' becomes 'rank' ('rank' can be a synonym of 'out-and-out').
'oddly' means one should take alternating letters.
The alternating letters of 'lies' are 'le'.
'rank'+'le'='RANKLE'
(Other definitions for rankle that I've seen before include "Continue to cause annoyance or bitterness" , "Continue to annoy" , "Cause continuous irritation" , "Cause persistent annoyance" , "Chafe" .)