Lowest point in cracked drain (5)
I believe the answer is:
nadir
'lowest point' is the definition.
(I've seen this before)
'cracked drain' is the wordplay.
'cracked' is an anagram indicator.
'drain' anagrammed gives 'NADIR'.
'in' acts as a link.
(Other definitions for nadir that I've seen before include "Very bottom, farthest from zenith" , "Drain to lowest level" , "least successful point" , "Drain into the lowest point (5)" , "Low point" .)