One level of cleric can add a ton of versatility to just about any spellcaster.
You get a bunch of good 1st level spells that scale well, a number of good ritual spells, good proficiencies, 3 additional cantrips (5 if you do arcana domain) and a Divine Domain feature that ranges from additional skill proficiencies to some cool abilities.
When I do this sort of build I make a point of picking cleric cantrips and spells to prepare that don't have an attack roll or save (buffs like bless, or a healing spell like healing word), so I can minimize my wisdom at 13 or 14, and so that I don't need to invest ASI's in improving an ability to go to the secondary class. The cleric's armor proficiency means that you don't need a dex score higher than 14 as well (or maybe dump dex entirely if you have heavy armor proficiency, like with life domain cleric, though watch those strength requirements), which means you can focus on your primary casting stat (charisma in your case) and then feats.
As you progress in sorcerer, make sure you have spells that get much better as they go to higher levels so that you can use your otherwise dead slots to good effect. Some examples: hold person/monster, animate dead, or major image.
Some examples of 1st cleric spells that are awesome throughout your career: sanctuary, cure wounds, healing word, and detect magic.
Cleric cantrips that are useful to take: guidance, light, mending, thaumatergy
If you make it to level 20, you lose the sorcerer's capstone ability.