I don't know about the Clover pen, but hairspray will take permanent marker out of Navy white uniforms. Might be worth a try for this ink.

I use the Clover pen whenever I need to mark dark fabric (which seems to be a lot). Always test a scrap first (I can say that as I have not followed my own instructions the first two or three times - LOL). Use a hot iron and steam. Then wash the fabric gently in cold water. Test the hairspray idea. I haven't tried that, but like ShirlinAZ said - it works on permanent marker, and better on ballpoint pen ink.

Thank you everyone for your input.

I had time today for the first time to tackle the problem. I took my spray bottle and filled it with cold water and really soaked the affected area then I put the iron on cotton setting and really steamed it. I am pleased to say that there is not a white mark now in sight.

I learnt a lesson from this.....always do a test piece on scrap fabric first.