Make dotty soiree start with drink (7)
I believe the answer is:
stipple
'make dotty' is the definition.
(I've seen this before)
'soiree start with drink' is the wordplay.
'start with' indicates taking the first letters.
'drink' becomes 'tipple' (tippling is a kind of drinking).
The first letter of 'soiree' is 's'.
's'+'tipple'='STIPPLE'
(Other definitions for stipple that I've seen before include "make dotty" , "It may make you see spots" , "Draw dotted; roughen" , "Use dots to draw, paint etc" , "Apply paint in dabs" .)