Drain off lowest part (5)
I believe the answer is:
nadir
'lowest part' is the definition.
The definition and answer can be both locations as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'drain off' is the wordplay.
'off' indicates an anagram.
'drain' is an anagram of 'NADIR'.
Can you help me to learn more?
(Other definitions for nadir that I've seen before include "Lowest point, or time of deepest depression." , "Drain (anag)" , "extremely low position" , "deep despair" , "Rock bottom" .)