One whinges a lot about railway, darling (7)
I believe the answer is:
crybaby
'one whinges' is the definition.
(someone who cries a lot)
'a lot about railway darling' is the wordplay.
'a lot' becomes 'c'.
'about railway' becomes 'ry' (abbreviation for railway. I am not sure about the 'about' bit.).
'darling' becomes 'baby' (I've seen this before).
'c'+'ry'+'baby'='CRYBABY'
Can you help me to learn more?
(Other definitions for crybaby that I've seen before include "Person too easily reduced to tears" , "One shedding tears frequently" , "(Very young?) weeper" , "Immature weeper" , "One prone to tears" .)