Triumphant queen abandoning last old American (10)
I believe the answer is:
victorious
'triumphant' is the definition.
(I know that triumphant can be written as victorious)
'queen abandoning last old american' is the wordplay.
I cannot really see how this works, but
'queen' could be 'r' (abbreviation for regina, e.g. in ER ) and 'r' is found within the answer.
'last' could be 't' (I've seen this in other clues) and 't' is present in the answer.
'old' could be 'o' (abbreviation) and 'o' is located in the answer.
'american' could be 'us' (abbreviation for United States) and 'us' is found within the answer.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for victorious that I've seen before include "winning" , "Triumphant" .)