Start to suggest leaving out sinister controller (8)
I believe the answer is:
svengali
'sinister controller' is the definition.
(I've seen this before)
'start to suggest leaving out' is the wordplay.
'start to' says to take the initial letters.
'out' indicates anagramming the letters (out can mean wrong or inaccurate).
The initial letter of 'suggest' is 's'.
'leaving' is an anagram of 'vengali'.
's'+'vengali'='SVENGALI'
(Other definitions for svengali that I've seen before include "dominating influence" , "Manipulative person" , "One exerting evil mental control over another" , "in novel form" , "Person exerting sinister control over another" .)