River and Asian peak gone over by travel writer (5)
I believe the answer is:
gorki
'writer' is the definition.
(Maxim Gorky, 1868-1936)
'river and asian peak gone over by travel' is the wordplay.
'river' becomes 'r' (abbreviation for river).
'and' says to put letters next to each other.
'asian peak' becomes 'KI' (resembles K1, mountain in Pakistan).
'gone over by' says to put letters next to each other (in a down clue, some letters go over others).
'travel' becomes 'go' (synonyms).
'r' next to 'ki' is 'rki'.
'rki' put after 'go' is 'GORKI'.
(Other definitions for gorki that I've seen before include "Former name of Nizhni Novgorod" , "writer from Russia" , "Nizhny Novgorod formerly; Russian author" , "Maxim --, Russian author" .)