Lowest point of broken drain (5)
I believe the answer is:
nadir
'lowest point' is the definition.
(I've seen this before)
'broken drain' is the wordplay.
'broken' indicates an anagram.
'drain' anagrammed gives 'NADIR'.
'of' is the link.
(Other definitions for nadir that I've seen before include "Low-water mark" , "Point opposite the zenith" , "businessman formerly escaping justice" , "deep despair" , "most unsuccessful point" .)