ラケットをしっかりにぎりなさい。

racket; paddle (in table-tennis)

indicates direct object of action; indicates subject of causative expression; indicates an area traversed; indicates time (period) over which action takes place; indicates point of departure or separation of action; indicates object of desire, like, hate, etc.

tightly (holding on); firmly; securely; strongly (built); solidly; sturdily; steadily; properly; well; sufficiently; hard (working, etc.); fully; completely; reliably; dependably; levelheadedly; shrewdly; wisely; cleverly

to clasp; to grasp; to grip; to clutch; to make (nigirizushi, rice ball, etc.); to form; to press into shape; to mold; to mould; to seize (power, etc.); to take hold of

to do