He tried to extract gold from St Michael (9)
I believe the answer is:
alchemist
'he tried to extract gold' is the definition.
The answer is a person as well as being a singular noun. This is suggested by the definition.
'from st michael' is the wordplay.
'from' is an anagram indicator (from the letters).
'st'+'michael'='stmichael'
'stmichael' with letters rearranged gives 'ALCHEMIST'.
Can you help me to learn more?
(Other definitions for alchemist that I've seen before include "magician" , "His hope to discover elixir of life" , "one trying to find the elixir of life" , "Seeker after gold" , "St Michael in role of one turning base metal into gold" .)