variable clutch bite ?

I have a An "R" reg i.8 Laguna estate, the clutch has a bite high on the release, if i am stuck in traffic for any length of time changeing gear constantly, the release bite starts to bite just off the floor, making it hard sometimes to engage a gear. If i push the pedal in and aout a few times it goes back to a high bite. can you tell me is it a fault with the clutch or the pedal and cable

John Williams