Climber writes novel about one alp primarily (8)
I believe the answer is:
wisteria
'climber' is the definition.
(the wisteria is a climbing plant)
'writes novel about one alp primarily' is the wordplay.
'novel' indicates anagramming the letters.
'about' indicates putting letters inside.
'one' becomes 'i' (Roman numeral).
'primarily' says to take the initial letters.
The first letter of 'alp' is 'a'.
'writes' is an anagram of 'wsteri'.
'wsteri' going around 'i' is 'wisteri'.
'wisteri'+'a'='WISTERIA'
(Other definitions for wisteria that I've seen before include "I swear it is a flowering vine" , "Vine with pendulous clusters of flowers" , "Climber" , "Climbing lilac-flowered shrub" , "A flower, I swear it" .)