Said to be tolerating the drink, a large volume of it! (6,3)
I believe the answer is:
number one
'it' is the definition.
(thesaurus)
'said to be tolerating the drink a large volume' is the wordplay.
I cannot quite understand how this works, but
'be' could be 'number' (numbering is a kind of being) and 'number' is located in the answer.
'drink' could be 'one' (eg 'a cold one') and 'one' is located in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
'of' is the link.
Can you help me to learn more?
(Other definitions for number one that I've seen before include "arch" , "top man?" , "Informally and numerically, oneself" , "it concerns egoists" , "Musical success" .)