Vision I mention in conversation (8)
I believe the answer is:
eyesight
'vision' is the definition.
(eyesight is your vision)
'i mention in conversation' is the wordplay.
'i' becomes 'eye' (I've seen this in other clues).
'mention' becomes 'cite' (to cite is to mention or quote).
'in conversation' indicates a 'sounds like' (homophone) clue.
'cite' sounds like 'sight'.
'eye'+'sight'='EYESIGHT'
(Other definitions for eyesight that I've seen before include "Faculty of vision" , "Showing sense" , "View" , "Perceptive faculty" , "Yes, eight required for vision" .)