Start to sample white wine in jar (5)
I believe the answer is:
shock
'jar' is the definition.
(I know that jar can be written as shock)
'start to sample white wine' is the wordplay.
'start to' indicates taking the first letters.
'white wine' becomes 'hock' (hock is a kind of white wine).
The first letter of 'sample' is 's'.
's'+'hock'='SHOCK'
'in' is the link.
(Other definitions for shock that I've seen before include "See 18" , "Jar" , "Unpleasant surprise" , "Jolt" , "Horrify - stroke" .)