### Clue: Smirk as Romeo is caught in trap (4)
### Answer: GRIN 
 ### Explanation: Definition: Smirk
 R(letter represented by "Romeo" in the phonetic alphabet) **contained in**(caught in) GIN(a trap for catching small animals).
Defn: A smile showing scorn or smugness, which could also be described as a grin, which is a turning up of the corners of the mouth to express an emotion.