This idea will get you into no trouble (6)
I believe the answer is:
notion
'this idea' is the definition.
(notion is a kind of idea)
'into no trouble' is the wordplay.
'trouble' indicates anagramming the letters.
'into'+'no'='intono'
'intono' with letters rearranged gives 'NOTION'.
'will get you' acts as a link.
(Other definitions for notion that I've seen before include "desire" , "Whimsical idea or small sewing article" , "Vague or whimsical idea" , "A vague and possibly incorrect opinion" , "Whim or fancy" .)