Where Arthur arrived frequently? (7)
I believe the answer is:
camelot
'where arthur' is the definition.
The definition suggests a singular noun which matches the answer.
'arrived frequently?' is the wordplay.
'arrived' becomes 'came' (coming is a kind of arriving).
'frequently?' becomes 'lot' (I can't justify this - if you can you should give a lot more credence to this answer).
'came'+'lot'='CAMELOT'
Can you help me to learn more?
(Other definitions for camelot that I've seen before include "Location of King Arthur's court" , "Idyllic situation" , "King Arthur's court - or JFK's" , "Mythical court" , "King Arthur's kingdom - or JFK's" .)