Searching for Clark gives several results across the County, including these wrt Woolastone and "Brookend" and "Tan". There may well be more under "Clarke", or in other areas eg Lydney, hopefully John you'll recognise the relevant names.
It seems that searches can only be for a surname OR a placename, but not both together, so please check for more relevant results, eg by text search. It does not give results for Chepstow, perhaps they are available elsewhere on a Monmouthshire based site ?.

Clark, AM
Woolastone, cottage (ruins), Brookend (GA/D2428/1/85, 633)

Clark, Maria
Woolastone, land, Bowlash (GA/D2428/1/85, 114)
Woolastone, house & land, Bowlash (GA/D2428/1/85, 116)
Woolastone, house, Brookend (GA/D2428/1/85, 436)
Woolastone, land, Smithy (GA/D2428/1/85, 437)
Woolastone, land, Piccadilly (GA/D2428/1/85, 439)
Woolastone, land, Bowlash (GA/D2428/1/85, 441)
Woolastone, tan yard, Brookend (GA/D2428/1/85, 543)

Much more details about each item can be gained from the site by clicking on the red hyperlinks.

"Tan House was built in the late 17th century and Brookend House, formerly the Woolaston Inn, bears the initials 'IMW 1713' on the gate-posts, which almost certainly stand for James and Mary Woodroffe (both d. 1728). (fn. 38)"

and to Francis Clark:
http://www.gwentarchives.gov.uk/media/26676/d4067mynyddbachshirenewton.html

"D4067/7 1. William Williams of par. Shirenewton, labourer. 2. Francis Clark of Chepstow, currier. MORTGAGE for £50 of premises as in (D4067/1). Endorsed: 28 April 1882 1. William Rapson of par. Chepstow, currier, and John Clark of par. Monmouth, tobacconist. 2. William Williams of par. Shirenewton, labourer. CONVEYANCE of premises as in mortgage above. Consideration: payment of principal and interest in mortgage above. 12 Sep 1879"

19 April 1848 - Hereford Journal:

"CHEPSTOW
Mr. Francis Clarke, currier, and Mr. Wm. Woodgate, grocer and baker, are appointed Overseers of the Poor, and Mr. Proctor, ironmonger, and Mr. Warren, draper, Surveyors of the Highway for the ensuing year. Chepstow, April 11."

Mike

“At Brookend a house known as Tan House in 1771 (fn. 135) was bought from the Hammond family by John Barrow in 1806 and converted between 1808 and 1833 by William Packer into a house with leather-room and drying loft. It was sold in 1849 to Francis Clark, a Chepstow currier, (fn. 136) whose business there was recorded up to 1876. (fn. 137) The tannery closed c. 1925 but some of the buildings remain.”

Mike