In no mood to be excited over Eastern religious structure (5,4)
I believe the answer is:
onion dome
'religious structure' is the definition.
The definition suggests a singular noun which matches the answer.
'in no mood to be excited over eastern' is the wordplay.
'to be excited' indicates an anagram.
'over' is a charade indicator (letters next to each other) (in a down clue, some letters go over others).
'eastern' becomes 'e' ().
'in'+'no'+'mood'='innomood'
'innomood' is an anagram of 'oniondom'.
'oniondom'+'e'='ONION DOME'
Can you help me to learn more?
(Other definitions for onion dome that I've seen before include "Byzantine structure?" , "exotic church feature" , "part of Russian church?" , "Feature of eastern churches" , "Architectural feature" .)