There was little to pick between the teams in the opening 20 minutes, each creating one chance. Pagham's Grant Radmore had his goalbound shot deflected for a corner.
But after an exchange of bookings, Joe Bennett was sin-binned on 28 minutes by the consistently officious and sensitive referee and Lancing took advantage four minutes later when centre half Will Berry found himself free on the edge of the box and finished with aplomb.
However almost as soon as he returned to the pitch, Bennett lashed his first touch home past a stationary home keeper. Bennett then tested the keeper again before half-time.
Lancing surged forward after the break and retook the lead soon after the restart. Parker was too strong for Barnes down the right and his hard cross was headed home by Ben Connolly.
Though Lancing were dominating possession, Connor Kelly had little to do in the Pagham goal. Pagham started to push the Lancers back with 15 minutes to go, Hambleton doing well on the right and putting his cross along the six-yard box but it eluded the oncoming Lions. Then George Bingham grazed the post with a header from a corner.
In the 84th minute, Lancing's Liam Hendy was shown a harsh red card and Pagham pushed on for the leveller. It arrived in the 92nd minute when Clarke was put through the centre and he showed great composure to round the keeper and slide the ball home.
The Lions could have grabbed all three points as Jared Rance hit the bar two minutes later. This was a good result for the Lions at a difficult place to play with Lancing used to playing on the slick artificial surface.
Pagham: Kelly, Atkinson, Barnes (Heryet), Clarke, Clark-Eden, Williamson, Rance, Hambleton, Radmore (Hawkes), Connolly (Bingham), Bennett. Unused subs: Hallett, Geoghegan.