Beginning northern climb (7)
I believe the answer is:
nascent
'beginning' is the definition.
(thesaurus)
'northern climb' is the wordplay.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'climb' becomes 'ascent' ('ascent' can be a synonym of 'climb').
'n'+'ascent'='NASCENT'
(Other definitions for nascent that I've seen before include "Newly-formed" , "not yet mature" , "Developing" , "Freshly generated" , "Emerging, in the process of being born" .)