Daughter finds diamonds in cube (4)
I believe the answer is:
dice
'cube' is the definition.
(I know that cube can be written as dice)
'daughter finds diamonds' is the wordplay.
'daughter' becomes 'd' (genealogical abbreviation).
'finds' means one lot of letters go next to another.
'diamonds' becomes 'ice' (slang term for diamonds).
'd'+'ice'='DICE'
'in' is the link.
(Other definitions for dice that I've seen before include "Gambling items" , "Random number generators" , "Small cube" , "Take a risk" , "Cubes used in gambling" .)