Rule riot out in secret (8)
I believe the answer is:
ulterior
'secret' is the definition.
(I've seen this before)
'rule riot out' is the wordplay.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
'rule'+'riot'='ruleriot'
'ruleriot' is an anagram of 'ULTERIOR'.
'in' is the link.
(Other definitions for ulterior that I've seen before include "Unrevealed" , "Secret extra (e.g. motive)" , "Hidden or undisclosed, perhaps motive" , "Beyond what is revealed or evident" , "(Of a motive) beyond what is stated" .)