Riddle about whiskey for Irish dean (5)
I believe the answer is:
swift
'irish dean' is the definition.
(Irish author and dean Jonathan Swift)
'riddle about whiskey' is the wordplay.
'riddle' becomes 'sift' (I've seen this before).
'about' means one lot of letters goes inside another.
'whiskey' becomes 'W' (alpha bravo charlie delta ...).
'sift' placed around 'w' is 'SWIFT'.
'for' acts as a link.
(Other definitions for swift that I've seen before include "Swallow-like bird" , "Bird; happening quickly" , "Hasty" , "Quick - writer" , "Expeditious" .)