Fuss over ruby, very dear (6)
I believe the answer is:
adored
'dear' is the definition.
(I've seen this in another clue)
'fuss over ruby' is the wordplay.
'fuss' becomes 'ado' (synonyms).
'over' says to put letters next to each other (in a down clue, some letters go over others).
'ruby' becomes 'red' (synonyms).
'ado'+'red'='ADORED'
'very' acts as a link.
(Other definitions for adored that I've seen before include "Doted on" , "Loved intensely" , "Loved dearly" , "Loved, venerated" , "Worshipped and revered" .)