To my view, in any campaign setting/game world, when talking about Nature DEITIES versus the "Nature/Natural World," in and of itself a whole, as pertains to Druids and druidism, you need at minimum, two distinct areas that could suit clerics well.
#1. Domain of the Wild. Your forests, your wilderness, UNTAMED and potentially dangerous Nature, animals (particularly undomesticated), the Hunt, perhaps also such abstracts as passions, fertility, lust and/or bloodlust. The deities of the untouched woods, mountains, other wild places; deities of or relating to the Animal kingdom, either generally or specifically (a god of lions, god mythologically associated with wolves, eagles, unicorns, etc...); the defenders of the wild; gods and patrons of those that deal in uncultivated nature for their livelihood such as hunters, trappers, timberworkers, just tribal/nomadic peoples, rangers. All such deities could have clerics using the Wild Domain.
#2. Domain of the Green. Your agriculture, crops and orchards, green growing things, TAMED and benevolent (or, at least, potentially beneficial) Nature, probably also some sway animals particularly domesticated, probably some sway over weather, the Harvest, possibly such abstracts as growth, health & [herbalism]medicine, midwifery/motherhood, rearing/teaching of the young. The deities of or relating to any of those things could have clerics using the Green Domain.