Shrewdness to capture terrible hound? It could be a Sherlock Holmes case (8)
I believe the answer is:
whodunit
'it could be a sherlock holmes case' is the definition.
(a whodunit is a murder mystery)
'shrewdness to capture terrible hound?' is the wordplay.
'shrewdness' becomes 'wit' (both can mean cleverness).
'to capture' indicates putting letters inside.
'terrible' indicates an anagram.
'hound' is an anagram of 'hodun'.
'wit' enclosing 'hodun' is 'WHODUNIT'.
(Other definitions for whodunit that I've seen before include "Question commonly posed" , "Informally, a detective story or play" , "Murderer revealed at the end, US style" , "Crime story (colloq.)" , "murder investigation" .)