The offer values the issued share capital of staff vetting specialist at approximately £14.7mln and represents a 23% premium to the last practicable share price.
Hanover Bidco said it had already received acceptances from more than 50% of shareholders, which is its acceptance target for the offer. Artemis Investment has also indicated it intends to accept the bid for its stake.
In a statement, Barney Quinn, Clearstar’s chairman said: "Having served as chairman of ClearStar since the IPO six years ago, I have been delighted to see the growth of our business, with the company now recognised as having market-leading employment and medical background screening technologies.
Up until the outbreak of the coronavirus (COVID-19) pandemic, ClearStar had a good start to the year and then saw excellent improvement from May onwards following the significant impact on revenues in March and April, the group's interim results, also released on Wednesday showed.
“However, we have not yet seen a return in much of our traditional business and the ongoing challenges created by the pandemic means that there remains significant near-term uncertainty. The Hanover offer provides us with financial certainty to continue building our business,” Quinn added.
ClearStar shares rose 18.5% to 38.5p.