Assumed one's invited for speech (7)
I believe the answer is:
guessed
'assumed' is the definition.
(I've seen this before)
'one's invited for speech' is the wordplay.
'one's invited' becomes 'guest' (someone invited somewhere).
'for speech' indicates a 'sounds like' (homophone) clue.
'guest' is a homophone of 'GUESSED'.
(Other definitions for guessed that I've seen before include "Conjectured" , "took a shot" , "Thought" , "Reckoned, judged" , "Made estimate or hazarded opinion" .)