Put an end to hard drink (6)
I believe the answer is:
scotch
This clue is a double definition.
'put an end' is the first definition.
(I've seen this before)
'hard drink' is the second definition.
(Scotch is an example)
'to' is the link.
(Other definitions for scotch that I've seen before include "Frustrate; quash" , "good spirits" , "Cut - wedge - whisky" , "tot" , "A drink; crush" .)