Vagrant blacked out a lot (10)
I believe the answer is:
bucketload
'a lot' is the definition.
(a bucketload is a lot of something)
'vagrant blacked out' is the wordplay.
'vagrant' is an anagram indicator (I've seen this in other clues).
'blacked'+'out'='blackedout'
'blackedout' anagrammed gives 'BUCKETLOAD'.
(Other definitions for bucketload that I've seen before include "great deal" , "Very large amount" .)