Here is a cool little circuit that will drive a signal which toggles at the clock frequency but is still driven from a register. It is very robust and upon wake up from a reset state will drive a clock like signal with the opposite phase of the clock but with the same frequency. To use the same phase as the clock itself, replace the XOR with an XNOR at the output.
If this circuit should be used as a clock for another block, consider the fact that the XOR gate at the output might introduce duty cycle distortion (DCD) due to the fact that many standard cell library XOR gates do not have a symmetrical behavior when transitioning from a logical 0 to a logical 1 and vice versa.
As an afterthought, it might be interesting to look at the similarities between this circuit and the “Double Edge Flip-Flop” I descried before.