Station on the Oxted line where one second is painful, time slipping away (7)

I haven't cracked this one yet — but the brilliant team at Fifteensquared have:

A charade of A (‘one’) plus S (‘second’) plus HURST, which is HURTS (‘is painful’) with the T moved one down (‘time slipping away’). ASHURST in Kent is a station on the Oxted line.