Collins Russian Dictionary 2nd Edition © HarperCollins Publishers 2000, 1997:
assent [əˈsɛnt] n согла́сие
vi
to assent (to)соглаша́ться (согласи́ться*perf) (на +acc)
* is used to mark translations which have irregular inflections. The Russian-English side of the dictionary gives inflectional information.