Weekly letter to a wandering nomad (6)
I believe the answer is:
monday
'weekly' is the definition.
(weekly occurrence)
'letter to a wandering nomad' is the wordplay.
'letter' becomes 'y' ().
'to' says to put letters next to each other (I've seen this in other clues).
'a wandering' indicates an anagram.
'nomad' with letters rearranged gives 'monda'.
'y' put after 'monda' is 'MONDAY'.
(Other definitions for monday that I've seen before include "Dynamo (anag.)" , "First weekday" , "Part of the week" , "Week day" , "May nod (anag.)" .)