Beginning last of Himalayan climb (7)
I believe the answer is:
nascent
'beginning' is the definition.
(thesaurus)
'last of himalayan climb' is the wordplay.
'last of' indicates one should take the final letters.
'climb' becomes 'ascent' ('ascent' can be a synonym of 'climb').
The last letter of 'himalayan' is 'n'.
'n'+'ascent'='NASCENT'
(Other definitions for nascent that I've seen before include "in early stages" , "Promising potential" , "Sent can (anag.)" , "Just setting out" , "being coined" .)