Ne'er-do-well wanting second something to drink (5)
I believe the answer is:
water
'something to drink' is the definition.
(water is a drink)
'ne'er-do-well wanting second' is the wordplay.
'ne'er-do-well' becomes 'waster' (both can mean an idle person).
'wanting' suggests deleting specific letters (to want something can mean to lack it or need it).
'second' becomes 's' (common abbreviation).
'waster' with 's' removed is 'WATER'.
(Other definitions for water that I've seen before include "Colourless, odourless and tasteless liquid" , "Transparent liquid" , "What can produce solution" , "Classical element" , "Inundate" .)