Notions said wrongly to include a foregone conclusion (5)
I believe the answer is:
ideas
'notions' is the definition.
(I've seen this before)
'said wrongly to include a foregone conclusion' is the wordplay.
'wrongly' is an anagram indicator.
'to include' indicates putting letters inside.
'conclusion' says to take the final letters.
The final letter of 'foregone' is 'e'.
'said' is an anagram of 'idas'.
'idas' enclosing 'e' is 'IDEAS'.
(Other definitions for ideas that I've seen before include "Thoughts or opinions" , "Notions, concepts" , "plans" , "Brain waves" , "thinking" .)