Illusory sight of silver buried in mud (6)
I believe the answer is:
mirage
'illusory sight' is the definition.
The definition and answer can be both related to thinking as well as being singular nouns.
Maybe there's an association between them I don't understand?
'silver buried in mud' is the wordplay.
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'buried in' is an insertion indicator (inserted letters get buried).
'mud' becomes 'mire' (synonyms).
'ag' going into 'mire' is 'MIRAGE'.
'of' is the link.
Can you help me to learn more?
(Other definitions for mirage that I've seen before include "Illusion caused by atmospheric refraction" , "fighter craft" , "unreal" , "Hallucination caused by hot air" , "Something illusory and unattainable" .)