Horses are usually started to respond to verbal cues (like the clicking) when they are started under saddle. The idea is to move them towards responding to the leg (calf squeezes NOT heel) and driving forward using your hips.
So start by doing both at the same time, then change to asking with calf first and if no response follow with calf and cluck.
Once she responds to calf alone you'll have your fix. If she doesn't then change calf squeeze to kick - because you will want to wake her up. Just be prepared for her to leap forward the first time you kick her so do NOT pull back with reins when whe leaps forward, instaed tell her softly "Good girl", pet her on the neck, then slowly bring her down to the gait (gallop down to canter or canter to trot or trot to walk) you wanted to start with.
The result will be that after a while she mapys better attention to you and will respond when you ask lightly with a calf squeeze, instead of waiting for a kick which she won't like.
Dressage is for Trainers!