American guy getting left trapped shows bravado (7)

I believe the answer is:
bluster
'bravado' is the definition.
(synonyms)
'american guy getting left trapped' is the wordplay.
I cannot really understand how this works, but
'american' could be 'us' (United States) and 'us' is found within the answer.
'left' could be 'l' (common abbreviation) and 'l' is present in the answer.
This may be the basis of the clue (or it may be nonsense).
'shows' acts as a link.
Can you help me to learn more?
(Other definitions for bluster that I've seen before include "Swaggering language" , "Show off" , "Boastful and bullying talk" , "Loud aggressive talk" , "Sound off" .)
