Not particularly. Even with Magic Guard as its ability, Clefable doesn't have extraordinarily good defences for stalling. Pokemon like Chansey/ Blissey/ Gliscor outclass it.
And besides, stall Pokemon usually have things like Toxic, Substitute, Protect, Leech Seed, Stun Spore, Encore and a recovery method, e.g. Roost/ Recover. Your Clefable only has Toxic, meaning it can't really stall since it will need to take hits and has no method of recovery.
Here's a good Gliscor stall set:
Gliscor @ Toxic Orb
Ability: Poison Heal
EVs: 200 HP, 56 Def, 252 Speed
- Earthquake/ Ice Fang
^ Good stalling Pokemon.