Visual symbolism (7)
I believe the answer is:
imagery
'visual symbolism' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for imagery that I've seen before include "Visual symbolism" , "Figures of speech" , "Figurative language, eg, in poem" , "Mental visions" , "The use of colourful language to make pictures in the mind" .)