Second drunk up to mix salad (4)
I believe the answer is:
toss
'mix salad' is the definition.
The answer and definition can be both acts as well as being singular nouns.
Perhaps there's a link between them I don't understand?
'second drunk up' is the wordplay.
'second' becomes 's' (common abbreviation).
'drunk' becomes 'sot' (synonyms).
'up' shows that the letters should be reversed in order (in down clue: letters go upwards).
's'+'sot'='ssot'
'ssot' reversed gives 'TOSS'.
'to' acts as a link.
Can you help me to learn more?
(Other definitions for toss that I've seen before include "Leave decision to chance" , "Throw lightly and casually" , "Throw carelessly" , "Raise a little money" , "Fling" .)