### Clue: Soldiers thus on retreat stop Roman bull, that ancient creature (10)
### Answer: TOROSAURUS 
 ### Explanation: Definition: ancient creature
 [ O.R.(abbrev. for "other ranks";non-commissioned soldiers) + **reversal of**(… on retreat) SO(thus;hence)] **contained in**(stop) TAURUS(Latin, the language of the ancient Romans, for "bull", the creature).
Defn: …, one of the dinosaurs.