Seen, heard, and quoted (5)
I believe the answer is:
cited
'quoted' is the definition.
('cite' can be a synonym of 'quote')
I cannot understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for cited that I've seen before include "Commended" , "Called for" , "Summoned" , "Quoted or mentioned as example" , "Made reference to -- edict (anag)" .)