Mental picture (5)
'mental picture' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for image that I've seen before include "personality" , "Picture; simile" , "Picture (involving one letter change from 10)" , "Dead ringer" , "Epitome" .)
(Other definitions for dream that I've seen before include "Distant ambition" , "Bedroom vision?" , "Fantasy; imagine" , "person to good to be true" , "dozy state" .)