Find out by investigating Ted, etc. (6)
I believe the answer is:
detect
'find out' is the definition.
(thesaurus)
'investigating ted etc' is the wordplay.
'ted etc' can be anagrammed to 'DETECT'.
Though, I'm not clear how this is indicated.
'by' is the link.
Can you help me to learn more?
(Other definitions for detect that I've seen before include "Perceive - discover" , "Discover the presence of, as Sherlock would" , "Find out - notice" , "Do what Morse did" , "Ascertain" .)