He was 2 sets down, and then 2-1 down in sets with a break against him, and he came back to force a fifth set, and took that to a tie-break. Hardly typical "choking", even if he was a little tired at the end.
Talking generally rather than about Cam, I do think hanging in there and coming back is a bit different from not getting across the line when in the box seat.
The former is admirable and shows very good spirit but I wouldn't describe it as clutch. The real clutch is being able to see that tight match out and when they seemingly have it in their hands some players do have problems.
