Unfortunate person to throw up after whiskey (6)
I believe the answer is:
wretch
'unfortunate person' is the definition.
(wretch is a kind of unfortunate person)
'throw up after whiskey' is the wordplay.
'throw up' becomes 'retch' (synonyms).
'after' says to put letters next to each other.
'whiskey' becomes 'W' (alpha bravo charlie delta ...).
'retch' put after 'w' is 'WRETCH'.
'to' is the link.
(Other definitions for wretch that I've seen before include "Unfortunate, miserable person" , "Good-for-nothing" , "Despicable person" , "Poor, pitiable person" , "Poor devil" .)