Blunt, independent married couple (6)
I believe the answer is:
impair
'blunt' is the definition.
(as in to blunt or impair a sense)
'independent married couple' is the wordplay.
'independent' becomes 'i'.
'married' becomes 'm'.
'couple' becomes 'pair' (synonyms).
'i'+'m'+'pair'='IMPAIR'
(Other definitions for impair that I've seen before include "Hinder" , "Cause weakening of, damage" , "'Mar, spoil (6)'" , "Reduce" , "Harm" .)