Calls on (6)
'calls on' is the definition.
('visit' can be a synonym of 'call on')
This is all the clue.
(Other definitions for visits that I've seen before include "Pays a call" , "Social calls" , "Calls in to see" , "Call to see" , "Comes by, drops in" .)
(Another definition for looks up that I've seen is " Seeks in reference book - takes eyes off book".)