I do not have a surname in my passport. How do I enter 'Given Name' and 'Family Name' in my UK visa application form?
There is an answer here http://www.immigrationboards.com/uk-tier-1-post-study-work-visas/no-surname-to-enter-online-dependent-visa-application-t122774.html from 2013 that indicates entering ‘-‘ is acceptable.
I had a similar issue with my wife’s passport. I had put '-' in the surname field.
Visa was granted by the high commission in Chennai. In the receipt her name was 'firstname' 'firstname'. However on the visa her name was only 'firstname'
She recently came to the UK, and there were no issues in immigration etc, except that the Indian immigration authority suggested that I include my name in my wife's passport.