One following whiskey carrier in this detective story (8)
I believe the answer is:
whodunit
'this detective story' is the definition.
(I've seen this before)
'one following whiskey carrier' is the wordplay.
'one' becomes 'unit' (synonyms).
'following' means one lot of letters go next to another.
'whiskey' becomes 'W' (phonetic alphabet: alpha, bravo, charlie etc.).
'carrier' becomes 'hod' (I've seen this before).
'w'+'hod'='whod'
'unit' after 'whod' is 'WHODUNIT'.
'in' acts as a link.
(Other definitions for whodunit that I've seen before include "American-style murder story" , "'A crime novel, colloquially (8)'" , "Informally, a detective story or play" , "thriller" , "Question commonly posed" .)