Be awfully neat when thrashed (6)
I believe the answer is:
beaten
'thrashed' is the definition.
('beat' can be a synonym of 'thrash')
'be awfully neat' is the wordplay.
'awfully' is an anagram indicator.
'neat' with letters rearranged gives 'aten'.
'be'+'aten'='BEATEN'
'when' acts as a link.
(Other definitions for beaten that I've seen before include "Defeated or mixed vigorously" , "Struck; defeated" , "Thrashed or whisked" , "Describes a path much trodden" , "Defeated or hit repeatedly" .)