Student or Learner
The only time Bollywood cast Rajnikant in an important role was in Anil Sharma's 'Farishtey', J. Om Prakash's 'Bhagwan Dada' and 'Wafadar', which were forgotten soon after. But except for his crisp Tamil accent, a Romeo-style red scarf, a cowboyish swagger, there was little to write home about his Bollywood career.
I think, cast = show, crisp = mild. Am I right?
Also, please explain the `write home'.
"Crisp" - sharp/clear.
"write home about" - colloquialism for "not much to say about" implying the actor's career is not particularly impressive.