Drink nearly all of what there is (5)
I believe the answer is:
total
'there is' is the definition.
I can't judge whether this definition defines the answer.
'drink nearly all of' is the wordplay.
'drink' becomes 'tot' (a small alcoholic drink).
'nearly' means to remove the last letter.
'all of' becomes 'all' (synonyms).
'all' with its final letter removed is 'al'.
'tot'+'al'='TOTAL'
'what' acts as a link.
Can you help me to learn more?
(Other definitions for total that I've seen before include "Utter" , "Complete, entire amount" , "final answer" , "Count" , "Including all" .)