### Clue: Plant, short, one of many that's died out in railway centre (5)
### Answer: DICOT 
 ### Explanation: Definition: Plant, short
D (died) *out in* **DI**(d)**COT** ("railway centre") 
*Didcot in Oxfordshire is known for its railway heritage, and dicot is short for "dicotyledon", which is a plant.