In reply to james1978:
The Upper Tier at Mangersta (beneath the bothy) has a bunch of shorter, generally easier routes, above a large platform about 40m above the sea - easy scramble down at the south end.
Other nearby crags, such as Rubh' an Taroin (really good E1 & E2), and The Painted Wall are above platforms/set back well away from the sea. Magic Geo is a deep geo, which should be fine in all but spring tides and wild seas. The Boardwalk Walls north of Uig are above a large non-tidal platform, so would also fit the bill, likewise Folded Wall at Aird Mhor Bhragair - lots fine sub-extreme routes.
Away from the hills, there are few single pitch crags with short approaches, though Crulivig Crag, just south of the bridge to Bernera is very convenient - 100m from road, with good routes from HVS upwards. The long routes on Tealasdale Slabs on Griomaval are worth the hour long approach - amazing panorama from the summit.