Praise be to Allaah.
Yes, it is permissible for one person to take care of
reciting the adhaan and leading the prayer. If the muezzin has more
knowledge of Qur’aan than anyone else, then he may lead the people present
in prayer as the imam. The same applies if the usual imam is absent and
appoints him to act in his stead. It is also permissible for him to be
appointed as the regular imam. End quote.
Shaykh ‘Abd-Allaah ibn Jibreen