A speculator, by the way, gets silver (4)
I believe the answer is:
stag
'a speculator' is the definition.
(type of stock market speculator)
'by the way gets silver' is the wordplay.
'by' says to put letters next to each other.
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'way' becomes 's' (Compass direction - South).
'gets' says to put letters next to each other.
'silver' becomes 'Ag' (Ag is the chemical symbol for silver).
't' after 's' is 'st'.
'st'+'ag'='STAG'
(Other definitions for stag that I've seen before include "Male animal" , "Hart" , "Unaccompanied man at party" , "Animal - for men only" , "Adult male red deer" .)