Weak female's abandoned bar (4)
I believe the answer is:
rail
'bar' is the definition.
(I know that rail is a type of bar)
'weak female's abandoned' is the wordplay.
'weak' becomes 'frail' (synonyms).
'female' becomes 'f' (common abbreviation).
'abandoned' is a deletion indicator.
'frail' with 'f' taken out is 'RAIL'.
(Other definitions for rail that I've seen before include "Scold, berate" , "Form of transport" , "Bar of rolled steel" , "Bar; waterbird" , "Abuse, scold" .)