Help child king to return ancient city (7)
I believe the answer is:
knossos
'ancient city' is the definition.
The definition suggests a singular noun which matches the answer.
'help child king to return' is the wordplay.
'help' becomes 'SOS' (emergency abbreviation SOS).
'child' becomes 'son' (male child).
'king' becomes 'K' (chess abbreviation).
'to return' says the letters should be written in reverse.
'sos'+'son'+'k'='sossonk'
'sossonk' written backwards gives 'KNOSSOS'.
Can you help me to learn more?
(Other definitions for knossos that I've seen before include "tourist attraction in Med" , "Minoan site on Crete" , "labyrinth" , "Minoan ruin in Crete" , "Ancient Cretan city" .)