Patchy picture pertaining to a law-giver (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 don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for mosaic that I've seen before include "Decorative work of small hard pieces" , "Design made of small pieces of colored stone or glass" , "Artistic design of glass or stones" , "Picture/pattern in small coloured pieces" , "Design of small pieces of colored stone or glass (6)." .)