City prominent in history or knowledge (4)
I believe the answer is:
york
'city' is the definition.
(York is a city)
'prominent in history or knowledge' is the wordplay.
'prominent in' indicates a hidden word (certain visible in the clue).
'YORK' is hidden in the letters of 'history or knowledge'.
(Other definitions for york that I've seen before include "'Made glorious summer by this sun of - - ' Shakespeare's Richard III" , "City called Eboracum by the Romans" , "Bowl out with ball pitching under bat" , "A place" , "City with a famous minster" .)