Diamonds disappear, five removed from German neighbour (6)
I believe the answer is:
danish
'german neighbour' is the definition.
(Germany and Denmark border each other)
'diamonds disappear five removed' is the wordplay.
'diamonds' becomes 'd' (abbreviation in bridge say).
'disappear' becomes 'vanish' ('vanish' can be a synonym of 'disappear').
'five' becomes 'v' ('V' can be a synonym of 'five').
'removed' indicates named letters should be taken away.
'vanish' with 'v' removed is 'anish'.
'd'+'anish'='DANISH'
'from' acts as a link.
(Other definitions for danish that I've seen before include "Scandanavian, pastry perhaps" , "Relating to one from Copenhagen, say" , "Flat cake - and party's his! (anag)" , "Dash in to the mysterious nationality" , "Copenhagen this capital" .)