Silver in one place of gold - just fancy (7)
I believe the answer is:
imagine
'fancy' is the definition.
(I know that fancy is a more specific form of the action imagine)
'silver in one place of gold' is the wordplay.
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'in' means one lot of letters goes inside another.
'one place of gold' becomes 'imine' (I am not sure about this - if you are sure you should believe this answer much more).
'ag' going within 'imine' is 'IMAGINE'.
'just' is the link.
Can you help me to learn more?
(Other definitions for imagine that I've seen before include "Suppose; conceive" , "Lennon song - dream" , "Picture in one's mind" , "Form a mental picture" , "John Lennon classic (just think of it!)" .)