Unmarried girl with rook finding English hillfort (6,6)
I believe the answer is:
maiden castle
'english hillfort' is the definition.
The definition suggests a singular noun which matches the answer.
'unmarried girl with rook' is the wordplay.
'unmarried girl' becomes 'maiden' (I've seen this before).
'with' says to put letters next to each other.
'rook' becomes 'castle' (synonyms).
'maiden'+'castle'='MAIDEN CASTLE'
'finding' is the link.
Can you help me to learn more?
(Other definitions for maiden castle that I've seen before include "impenetrable stronghold" , "Ancient hill fort in Dorset" .)