Bandage decoy plugged by one American's gun (8)
I believe the answer is:
ligature
'bandage' is the definition.
(I've seen this before)
'decoy plugged by one american's gun' is the wordplay.
'decoy' becomes 'lure' (synonyms).
'plugged by' means one lot of letters goes inside another (plug can mean to block up a gap).
'one' becomes 'i' (Roman numeral).
'american's gun' becomes 'gat' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'i'+'gat'='igat'
'lure' enclosing 'igat' is 'LIGATURE'.
Can you help me to learn more?
(Other definitions for ligature that I've seen before include "Bandage, binding" , "Thread used to constrict the flow of blood" , "Character combining two letters" , "It bids to restrict blood flow" , "Thread for sealing blood vessels" .)