Flat obtained by a woman in the Fifties (5)
I believe the answer is:
level
'flat' is the definition.
(synonyms)
'a woman in the fifties' is the wordplay.
'a woman' becomes 'eve' (Eve is an example).
'in the' is an insertion indicator.
'fifties' becomes 'll' (the Roman numeral for 50 written twice).
'eve' put inside 'll' is 'LEVEL'.
'obtained by' is the link.
(Other definitions for level that I've seen before include "Straight, even" , "Having a flat, horizontal surface" , "Neither winning, nor losing" , "Flush" , "Flatten" .)