Translation:Tini is suspected of receiving a letter from Andi's lawyer.
Duga = suppose, estimate, guess ... di- is the prefix used to make verbs passive ... diduga = is supposed to (suspected of).
Menerima is the me- verb of terima (receive ... terima kasih = thank you ... but literally means 'receive love'). Pengacara is a lawyer or litigator ... acara means schedule / agenda, and has only a limited connection to an occupation formed by adding the prefix peng- Hope this helps ... I have covered as much as I know (with some help from googling the base word, acara).