Understood husband is a fan of dark clothing (4)
I believe the answer is:
goth
'a fan of dark clothing' is the definition.
(goths wear dark clothing)
'understood husband' is the wordplay.
'understood' becomes 'got' (getting is a kind of understanding).
'husband' becomes 'h' (abbreviation).
'got'+'h'='GOTH'
'is' acts as a link.
(Other definitions for goth that I've seen before include "Uncivilised type" , "Teutonic invader of the Roman Empire" , "Girl in black perhaps" , "Old invader" , "Old German; rock style" .)