The bottom drain is broken (5)
I believe the answer is:
nadir
'the bottom' is the definition.
(thesaurus)
'drain is broken' is the wordplay.
'is broken' indicates anagramming the letters.
'drain' is an anagram of 'NADIR'.
(Other definitions for nadir that I've seen before include "Lower one cannot get!" , "extremely low position" , "lowest of the low" , "It's the depths" , "Point of greatest despair" .)