In Cumbria, the lad returns by railway (5)
I believe the answer is:
rydal
'in cumbria' is the definition.
The definition suggests a singular noun which matches the answer.
'the lad returns by railway' is the wordplay.
'returns' shows that the letters should be reversed in order.
'by' is a charade indicator (letters next to each other).
'railway' becomes 'ry' (abbreviation for railway).
'lad' back-to-front is 'dal'.
'dal' put after 'ry' is 'RYDAL'.
Can you help me to learn more?
(Other definitions for rydal that I've seen before include "Village near Ambleside" , "where Wordsworth once lived" , "Lakeland water" , "Village near 23 across" , "Wordsworth's Mount" .)