North America, mostly dreadful, the worst place (5)
I believe the answer is:
nadir
'worst place' is the definition.
The answer and definition can be both locations as well as being singular nouns.
Maybe they are linked in a way I don't understand?
'north america mostly dreadful' is the wordplay.
'north america' becomes 'na'.
'mostly' means to remove the last letter (most but not all of the word).
'dreadful' becomes 'dire' (synonyms).
'dire' with its last letter taken away is 'dir'.
'na'+'dir'='NADIR'
'the' is the link.
Can you help me to learn more?
(Other definitions for nadir that I've seen before include "Point opposite the zenith" , "pits" , "The lowest point of anything" , "extremely low position" , "All-time low" .)