Know I study fifty puzzles — not following? (8)
I believe the answer is:
identify
'know' is the definition.
(thesaurus)
'i study fifty puzzles not following?' is the wordplay.
I cannot quite see how this works, but
'i' is found in the answer.
'study' could be 'den' (I've seen this before) and 'den' is located in the answer.
'following?' could be 'f' (used when citing page numbers etc) and 'f' is found within the answer.
This may be the basis of clue (or it may be nonsense).
(Other definitions for identify that I've seen before include "Empathise" , "Establish who a person is" , "Detect" , "Establish who one is" , "Sympathise" .)