Americans releasing article about old age (5)
I believe the answer is:
yonks
'age' is the definition.
(I have seen 'An age' mean 'yonks' so perhaps 'age' could also mean 'yonks')
'americans releasing article about old' is the wordplay.
'americans' becomes 'yanks' (Yank is an example).
'releasing' suggests deleting specific letters.
'article' becomes 'a' (the indefinite article in English).
'about' indicates putting letters inside.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'yanks' with 'a' taken out is 'ynks'.
'ynks' going around 'o' is 'YONKS'.
(Other definitions for yonks that I've seen before include "An age" , "Slang for a long time, ages" , "Donkey's years!" , "Ages (informal)" , "Many years (slang)" .)