fantom and ray, thanks for the responses. I've done sewing repairs on stuff before, which works well, but was interested in trying the glue a patch option, so glad to see that rubber cement will work reasonably well. I've been looking at this little hole for ages now, so knowing that the glue option does work, I'm willing to give it a try.
cheers
On the other hand, you could just ignore it. Lycra doesn't run so it's not really an issue. I've got shorts and tights that have had holes in the for 10 years or more without issues.