Very impressive ace, first person to get total read out (7)
I believe the answer is:
awesome
'very impressive' is the definition.
(I've seen this in another clue)
'ace first person to get total read out' is the wordplay.
'ace' becomes 'a' (abbreviation).
'first person' becomes 'we' (first-person plural pronoun).
'to get' says to put letters next to each other.
'total' becomes 'sum' (synonyms).
'read out' shows a homophone (sound like).
'sum' sounds like 'some'.
'a'+'we'+'some'='AWESOME'
(Other definitions for awesome that I've seen before include "Inspiring admiration or wonder" , "Generating fear and wonder" , "Very imposing, inspiring wonder" , "Inspiring admiration - wonderful!" , "Overwhelming or dreadful to behold" .)