Wanderers took the lead with only meaningful attack of the game, in the 11th minute, immediately after they had survived going behind when Argyle striker Nick Chadwick's shot on the turn cannoned off a post.
Chairboys midfielder Matt Spring, back in the team after suspension, dispossessed his opposite number Luke Young to play in McClure.
The striker, who had also been recalled after a ban, took the ball in his stride and shot across home goalkeeper Rene Gilmartin to bring the home side's five-game unbeaten December run to an end.
It was tough on the Pilgrims, who made all the running throughout the entire game, with Chadwick, Robbie Williams, Paris Cowan-Hall and Conor Hourihane all thwarted by Wycombe's overworked defence in the first half.
It was much more of the same after the interval, with Cowan-Hall hitting the bar and both Chadwick and Darren Purse heading narrowly wide.