Defeat not considered after article is cut short (6)
I believe the answer is:
thrash
'defeat' is the definition.
(I know that thrash is a kind of beat)
'not considered after article is cut short' is the wordplay.
'not considered' becomes 'rash' (thoughtless or not considered properly).
'after' means one lot of letters go next to another.
'article' becomes 'the' (the definite article in English).
'is cut short' means to remove the last letter.
'the' with its last letter taken off is 'th'.
'rash' put after 'th' is 'THRASH'.
(Other definitions for thrash that I've seen before include "Beat severely or defeat thoroughly" , "Trounce, beat soundly" , "Beat thoroughly or make wild movements" , "Beat violently" , "Punish" .)