The affix kyaṅ in the sense of exerting in the dishonesty, is employed after the word kaṣṭa 'mischief' when the latter has the 4th case-affix in construction.,
Thus, कष्टाय कर्मणे क्रामति = कष्टायते 'he is assiduous for trouble, i.e. he is assiduous in the commission of dishonesty, or he plots'.
Vart:- The affix क्यङ्, comes in the sense of exerting in evil, after the words सत्र, कष्ट, कक्ष, कृच्छ्र and गहन; as, सत्रायते, कष्टायते, कक्षायते, कृच्छ्रायते, and गहनायते ।
When the sense is not of 'evil', the affix is not added, as अजः कष्टं क्रामति.,