23057a57b4 introduces a shadowed defvar org-clock-effort by copying the definition from org-clock.el to org.el without deleting it in org-clock.el. If a forward declaration was intended, then the defvar in org.el should provide no initial value, otherwise (since org-clock.el requires org.el anyway) the duplicate definition in org-clock should be removed.
Regards, Achim. -- +<[Q+ Matrix-12 WAVE#46+305 Neuron microQkb Andromeda XTk Blofeld]>+ Factory and User Sound Singles for Waldorf rackAttack: http://Synth.Stromeko.net/Downloads.html#WaldorfSounds