Cleanse a newborn’s bottom going over the worst bit (5)
I believe the answer is:
nadir
'worst bit' is the definition.
Although both the answer and definition are singular nouns, I cannot see how they can define each other.
'cleanse a newborn's bottom going over' is the wordplay.
'cleanse' becomes 'rid' (I've seen this in another clue).
'bottom' suggests the final letters.
'going over' says the letters should be written in reverse.
The final letter of 'newborn' is 'n'.
'rid'+'a'+'n'='ridan'
'ridan' reversed gives 'NADIR'.
'the' acts as a link.
Can you help me to learn more?
(Other definitions for nadir that I've seen before include "Point of greatest despair" , "All-time low" , "Lower one cannot get!" , "Lowest point, or time of deepest depression." , "pits" .)