A liberal method succeeded constantly (6)
I believe the answer is:
always
'constantly' is the definition.
(I've seen this before)
'a liberal method succeeded' is the wordplay.
'liberal' becomes 'l' (abbreviation).
'method' becomes 'way' (way of doing something).
'succeeded' becomes 's' (genealogical abbreviation).
'a'+'l'+'way'+'s'='ALWAYS'
(Other definitions for always that I've seen before include "Every time" , "Irving Berlin's enduring song" , "At all times" , "Invariably" , "Forevermore" .)