Just to keep this from languishing, I'd do something like this. First synthesis an o/p directing group, for example a methyl or a hydroxy group. Nitration should give an o/p-mixture from which the para isomer can be isolated. If this were done on the phenol, then reduction, diazotization, and cyanide can give the desired product. If from toluene, he nitro group can be converted to the phenol, oxidation of the methyl group to a carboxylic acid, conversion to an amide and dehydration to the nitrile would also give the product.