On reflection it failed to get straightened out (6)
I believe the answer is:
tidied
'straightened out' is the definition.
('tidy' can be a synonym of 'straighten out')
'on reflection it failed' is the wordplay.
'on reflection' says the letters should be written in reverse.
'failed' becomes 'died' ('die' can be a synonym of 'fail').
'it' in reverse letter order is 'ti'.
'ti'+'died'='TIDIED'
'to get' acts as a link.
(Other definitions for tidied that I've seen before include "Cleared away" , "Cleaned up" , "Given order" , "Arranged neatly" , "Neatened" .)