OK to go with expert (8)
I believe the answer is:
passable
'ok' is the definition.
(thesaurus)
'go with expert' is the wordplay.
'go' becomes 'pass' (passing is a kind of going**).
'with' is a charade indicator (letters next to each other).
'expert' becomes 'able' (I've seen this in other clues).
'pass'+'able'='PASSABLE'
'to' acts as a link.
(Other definitions for passable that I've seen before include "okay?" , "examinations should be!" , "Fair" , "All right" , "Good enough to be acceptable" .)