Unfortunately rudeness almost is guaranteed (7)
I believe the answer is:
ensured
'is guaranteed' is the definition.
(I've seen this in another clue)
'unfortunately rudeness almost' is the wordplay.
'unfortunately' is an anagram indicator (a bad or unfortunate spelling).
'almost' means to remove the last letter (most of the word but not all of it).
'rudeness' with its final letter removed is 'rudenes'.
'rudenes' anagrammed gives 'ENSURED'.
(Other definitions for ensured that I've seen before include "Saw to it" , "guaranteed" , "Made certain for end user" , "Determined" , "Made certain, clinched" .)