Disseminates advertisement in press arrangement (7)
I believe the answer is:
spreads
'disseminates' is the definition.
('spread' can be a synonym of 'disseminate')
'advertisement in press arrangement' is the wordplay.
'advertisement' becomes 'ad' (short for advert).
'in' means one lot of letters goes inside another.
'arrangement' is an anagram indicator.
'press' with letters rearranged gives 'spres'.
'ad' inserted within 'spres' is 'SPREADS'.
(Other definitions for spreads that I've seen before include "Extends; elaborate meals" , "Extends the feasts?" , "Cover the surface of, as with butter" , "Lays out" , "Distributes or disperses widely" .)