New arena mostly good in bad region (2-2,4)
I believe the answer is:
no-go area
'bad region' is the definition.
The definition suggests a singular noun which matches the answer.
'new arena mostly good' is the wordplay.
'new' is an anagram indicator.
'mostly' means to remove the last letter.
'good' with its final letter removed is 'goo'.
'arena'+'goo'='arenagoo'
'arenagoo' anagrammed gives 'NO-GO AREA'.
'in' is the link.
Can you help me to learn more?
(Other definitions for no-go area that I've seen before include "One mustn't enter it" , "Forbidden zone" , "Region where entry is dangerous, impossible, or forbidden" , "Region that's dangerous or to which entry is forbidden" , "Dangerous territory" .)