If you want a simple redstone clock here you go. All you need is 2 Command blocks for this. Just look At The Picture To See How To Place Them!

Command Block:
/give @p minecraft:command_block



Top Command Block:
/fill ~ ~-1 ~1 ~ ~-1 ~ redstone_block



Bottom Command Block:
/fill ~ ~1 ~ ~ ~1 ~1 stone



Be sure to Do
/gamerule DoCommandBlockOutput false before because your chat will be spammed








Should Be This Format

Command Block
Redstone Block
Command Block