In a fitting manner (13)
'in a fitting manner' is the definition.
(I've seen this in another clue)
This is all the clue.
(Other definitions for aptly that I've seen before include "In a suitable manner" , "as is fitting" , "Appropriately" , "In suitable fashion" , "Fittingly" .)
(Other definitions for appropriately that I've seen before include "Aptly" , "Suitably, properly" .)
(Other definitions for duly that I've seen before include "As a matter of course" , "As might be expected" , "Following proper procedure" , "In proper form, time" , "In a proper manner" .)