A bed is unmade? That's not fair! (6)
I believe the answer is:
biased
'not fair' is the definition.
(I've seen this in another clue)
'a bed is unmade?' is the wordplay.
'unmade?' is an anagram indicator (the original order is unmade or damaged).
'a'+'bed'+'is'='abedis'
'abedis' with letters rearranged gives 'BIASED'.
'that's' is the link.
(Other definitions for biased that I've seen before include "Having prejudice" , "Prejudiced or influenced in favour or against" , "Prejudiced or partisan" , "Favouring one person or side over another" , "not fair" .)