As Tom said, so in that case, select that one clip you want as a range, then export. If a rangs is selected in a Timeline, when you export, then only that section gets exported. Otherwise, you get the whole Timeline, black disabled clips and all.
just to answer both helpful responses. Yes, I disabled the clips I didn't want to export and highlighted the clip I did want to export. The disabled clips were 'dark', and the enabled clip (the very short one) was highlighted by selecting all the components with the mouse.
You mention 'export' and I am using 'share', which I assumed is the only option when rendering and saving a file for youtube etc. Or is 'export' another option?
any further suggestions would be very welcome, it remains a mystery.
Many thanks for this tip. I will give this a try. I have used FCPX on other projects and maybe I just worked with only one clip in the time line. Perhaps this 'marking' is necessary when there are more than one clip in the timeline?
thanks for this. I experimented with using markers and that did the job. BUT I noticed that even though I had highlighted just one clip and the others were disabled, when I inserted the markers they appeared over another clip, not the one I was exporting. The clips were the correct length, but why didn't the marked area appear over the clip I was actually exporting, but over a completely unrelated clip, that was also disabled?