What's on plate a worry if tipped over finery (7)
I believe the answer is:
regalia
'finery' is the definition.
(synonyms)
'what's on plate a worry if tipped' is the wordplay.
'what's on plate' becomes 'reg' (a number plate shows a car's registration number).
'worry' becomes 'ail' (I've seen this before).
'if tipped' is a reversal indicator.
'ail' back-to-front is 'lia'.
'reg'+'a'+'lia'='REGALIA'
'over' acts as a link.
(Other definitions for regalia that I've seen before include "Insignia of royalty or office" , "Ceremonial emblems of high office" , "Array" , "Orb and sceptre etc" , "Royal trappings" .)