Endless (12)
There are a few possibilities for this:
interminable
'endless' is the definition.
(I know that endless can be written as eternal)
This is the entire clue.
(Other definitions for eternal that I've seen before include "Never failing" , "Forever or unchanging" , "Without beginning or end" , "unchanged by time" , "Permanent, without end" .)
'endless' is the definition.
(thesaurus)
This is all the clue.
(Other definitions for nonstop that I've seen before include "Without pause or interruption" , "Round-the-clock, unceasing" , "Never pausing" , "Incessant" , "Done without pause" .)
'endless' is the definition.
(I know that endless can be written as interminable)
This is all the clue.
(Other definitions for interminable that I've seen before include "Endless" , "Such a long wait" , "Tedious" , "Unending" , "Long drawn-out" .)