Article written by married geezer (3)
I believe the answer is:
man
'geezer' is the definition.
(I've seen this before)
'article written by married' is the wordplay.
'article' becomes 'an' (English indefinite article).
'written by' means one lot of letters go next to another.
'married' becomes 'm' (abbreviation, e.g. in genealogy).
'an' put after 'm' is 'MAN'.
(Other definitions for man that I've seen before include "-- Friday" , "Adult human male" , "just one" , "Irish Sea isle" , "Homo sapiens" .)