Baker Street detective (6)
I believe the answer is:
holmes
'baker street detective' is the definition.
(I've seen this before)
This is the entire clue.
(Other definitions for holmes that I've seen before include "One good at interpreting clues" , "Our 1/4 Across [GOLD MEDALLIST] in 2004" , "Watson's idol" , "Sherlock . . . . . . is a great fictional detective" , "Conan Doyle creation" .)