Escaped backing welfare age dropping (4)
I believe the answer is:
flew
'escaped' is the definition.
(I've seen this in another clue)
'backing welfare age dropping' is the wordplay.
'backing' says the letters should be written in reverse.
'age' becomes 'era' (both can mean a long time).
'dropping' is a deletion indicator (some letters drop out).
'welfare' in reverse letter order is 'eraflew'.
'eraflew' with 'era' taken away is 'FLEW'.
(Other definitions for flew that I've seen before include "Took off" , "Rushed < from local flat" , "Dashed" , "Travelled by plane" , "lip" .)