Prepare to swallow a red wine at the start (4)
I believe the answer is:
chew
'prepare to swallow' is the definition.
(I've seen this in another clue)
'a red wine at the start' is the wordplay.
'a red' becomes 'che' (as in Che Guevara, a communist or 'red').
'at the start' indicates taking the first letters.
The first letter of 'wine' is 'w'.
'che'+'w'='CHEW'
(Other definitions for chew that I've seen before include "Bite and grind food in the mouth" , "Try to eat" , "Masticate, grind between teeth" , "Reflect on" , "Treat for dog" .)