The one place that couldn’t be better (5)
I believe the answer is:
ideal
'the one place that couldn't be better' is the definition.
Although both the answer and definition are singular nouns, I cannot understand how one could define the other.
'the one place' is the wordplay.
'the one' becomes 'i' (Roman numeral).
'place' becomes 'deal' (I can't explain this - if you can you should believe this answer much more).
'i'+'deal'='IDEAL'
Can you help me to learn more?
(Other definitions for ideal that I've seen before include "Very eager (to see)" , "Embodying perfection" , "Cutting/stabbing weapons" , "Exemplar" , "Most suitable" .)