Bust of Caesar finally placed on support (4)
I believe the answer is:
raid
'bust' is the definition.
(I've seen this before)
'caesar finally placed on support' is the wordplay.
'finally' indicates one should take the final letters.
'placed on' means one lot of letters go next to another.
'support' becomes 'aid' ('aid' can be a synonym of 'support'**).
The last letter of 'caesar' is 'r'.
'r'+'aid'='RAID'
'of' is the link.
(Other definitions for raid that I've seen before include "Assault, attack" , "Invasion" , "Search by police without warning" , "Sudden and surprise attack" , "Sudden short attack" .)