Solemnly renounce (6)
I believe the answer is:
abjure
'solemnly renounce' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for abjure that I've seen before include "Renounce, forswear" , "Reject" , "Forswear, recant" , "(Solemnly) give up" , "Disavow" .)