Cautious about silver and yen (4)
I believe the answer is:
cagy
'cautious' is the definition.
(similar in meaning)
'about silver and yen' is the wordplay.
'about' becomes 'c' (abbreviation for circa).
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
'and' says to put letters next to each other.
'yen' becomes 'y' (resembles the symbol for the currency of Japan).
'c'+'ag'+'y'='CAGY'
(Other definitions for cagy that I've seen before include "Cautiously secretive" , "giving little away" , "Cautious and wary" , "Like bars" , "Guarded, discreet" .)