Patchy picture of a lawgiver (6)
I believe the answer is:
mosaic
'patchy picture' is the definition.
'mosaic' can be an answer for 'picture' (mosaic is a kind of picture). I'm not sure about the 'patchy' bit.
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for mosaic that I've seen before include "Tessellated picture" , "from one of the prophets" , "Like the Commandments" , "Decorative work of small hard pieces" , "Tessellated design" .)