After early Clyde pressure, during which Mark Reilly kicked a John Potter effort off the line, St Mirren had the majority of territorial advantage. Brian McGinty saw a header drift just wide after a clever interchange between Allan Russell and John O'Neill.
Clyde keeper, Bryn Halliwell, tried to usher the ball behind for a goal-kick but McGinty dispossessed him and passed inside for O'Neill, but Simon Mensing made a splendid block on the forward's strike.
St Mirren's Kirk Broadfoot headed a Simon Lappin header over the bar, and O'Neill had another shot saved. Potter miscued a headed clearance, but Russell's drive dipped over as Saints sought to capitalise on their superiority. From another Lappin free-kick, O'Neill headed firmly into the net but a flag had gone up promptly and the game remained scoreless.
In the second half, Saints continued to press and O'Neill went close with a header from Russell's cross. McGinty fired another shot against the bar, but Alex Burns gave notice of Clyde's menace when he curled a free-kick beyond the defensive wall, forcing Craig Hionchcliffe into a splendid diving save.
All the substitutions failed to alter things, but there was a deluge of cards from referee Underhill - six in the last five minutes - which resulted in dismissals for St Mirren's Hugh Murray and Clyde's Darren Sheridan.
In the very last seconds, Broadfoot met a curling free-kick on the volley and seemed to have secured a dramatic last-gasp victory for St Mirren, but Halliwell took off in thrilling fashion and tipped the ball over the bar.