Second Commandment subject (5)
I believe the answer is:
idols
'second commandment subject' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for idols that I've seen before include "False gods" , "Solid (anag.)" , "Graven images sometimes worshipped" , "Objects of worship" , "Effigies worshipped as gods" .)