The Old French definitions are hard to come by, but the language comes from Latin, and German. But looking at similar words, cloister, enclosure...'Clos' is an Old French definition of enclosure. The best overview of the words transition from the Latin to the more modern French is at this website: www.word-origins.com/definition/close.html

Medieval cloisters had small courtyards near the hospitals where the physic or medicinal gardens, and their roses were planted for easy accessibility. The "Apothecary rose" is a famous one.

Jean-Baptiste-Bonaventure de Roquefort's 1808 "Glossaire de la langue Romane" (Google books) includes definitions for:
1. Closages: "champs voisins d'une ville, et espece de fief"
'Champs' meaning field, farm, or yard, and 'voisins' meaning neighbors, or basically a shared 'village green'. The Latin 'spece' means cave, and that would be a type of enclosure, but the French for coppicing is "recépage" (see the definition below). Google wasn't much help, they said 'espece' was 'species' and that really didn't make sense.

2. Closeau: "petit jardin de paysan, un petit clos ferme de haises ou de fagotage"
The first part translates, "A peasant's garden, a small enclosed farm...) the rest of the definition is difficult, but it could mean "of hazel or faggots", which would mean brush, or a hedgerow.

The German 'hasel' for hazel, or hazelnut, could also be a transition to the word 'hedge'. Fagotage is an act of making faggots, cutting (coppicing) brush to form a dense barrier, or weaving young growth into itself to form a wattle fence, or dense hedgerow.

Coppicing shrubs and trees within a hedgrow was a method to thicken it quickly, and hazelnut trees or shrubs respond very quickly when cut to the ground, sending out runners when their roots are disturbed. Forming the cut brush into bundles of faggots is a fast method of making a barrier, and if the freshly cut branches are mudded in they can root on their own and fill in the gaps of a hedgerow. Cut branches were also used for baskets, and many other purposes.

So 'clos', a small enclosed courtyard, is a lovely word with lots of history, and brings up lots of visual imagery.