Was not prepared to be detective's assistant (6)
I believe the answer is:
watson
'be detective's assistant' is the definition.
The definition suggests a singular noun which matches the answer.
'was not prepared' is the wordplay.
'prepared' is an anagram indicator.
'was'+'not'='wasnot'
'wasnot' is an anagram of 'WATSON'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for watson that I've seen before include "Sherlock Holmes's doctor companion" , "Doctor colleague of Sherlock Holmes" , "Holmes' associate" , "Tom - - , golfer" , "Holmes's associate" .)