American vessel brought back monarch from abroad (4)
I believe the answer is:
raja
'monarch from abroad' is the definition.
I can't judge whether this defines the answer.
'american vessel brought back' is the wordplay.
'american' becomes 'a' (common abbreviation - e.g. in organisation names).
'vessel' becomes 'jar' (type of container).
'brought back' says the letters should be written in reverse.
'a'+'jar'='ajar'
'ajar' in reverse letter order is 'RAJA'.
Can you help me to learn more?
(Other definitions for raja that I've seen before include "Indian prince or king" , "sovereign" , "Prominent Indian" , "High Indian position" , "Asian prince or king" .)