As in, an Indian take away or delivery meal.
I find it quite odd to hear one specific type of cuisine referred to like this. Would you say “ we’re going for a French tonight” or “he invited me to his place for an Italian”? Somehow it seems dismissive and disrespectful.
For full disclosure, I’m not Indian but my husband is of Asian ancestry and our children have dual heritage. I’m British (first generation migrant). I was born and brought up in North America and can’t remember the expression ‘an Indian’ ever being used as short for Indian food before I moved to Britain.