Lowest point in the drain, perhaps (5)
I believe the answer is:
nadir
'lowest point' is the definition.
(I've seen this before)
'drain perhaps' is the wordplay.
'perhaps' indicates an anagram.
'drain' with letters rearranged gives 'NADIR'.
'in the' is the link.
(Other definitions for nadir that I've seen before include "Drain to lowest level" , "Low-water mark" , "extremely low position" , "You can't sink lower!" , "worst-case scenario?" .)