。
A party was held in honor of the visiting writer.
Literal
Visit-mid [attributive-の] writer [to-に] respect [object-を] express-and party [subject-が] was-held.
~中 attached to a suru-verb stem (来訪 → 来訪中) means 'in the middle of / currently doing X' — 'currently visiting.' 敬意を表する ('to express respect') is a stiff/formal collocation, typical of official ceremony language. The whole sentence has a news-report register.