Call on again (7)
I believe the answer is:
revisit
'call on again' is the definition.
('visit' can be a synonym for 'call on' so perhaps 'revisit' is OK for 'call on again')
This is all the clue.
(Other definitions for revisit that I've seen before include "Pay further call" , "Go back to (place)" , "comeback?" , "repeated call?" , "making further call!" .)