Most recent trial at Los Angeles (6)
I believe the answer is:
latest
'most recent' is the definition.
('late' can be similar in meaning to 'recent')
'trial at los angeles' is the wordplay.
'trial' becomes 'test' (synonyms).
'at' is a charade indicator (letters next to each other) (I've seen this in other clues).
'los angeles' becomes 'LA' (abbreviation).
'test' put after 'la' is 'LATEST'.
(Other definitions for latest that I've seen before include "Most recent report" , "Most up-to-date" , "hot bit of news" , "Most recent (news)" , "Brand new, just out" .)