Developing northern trip up a mountain? (7)
I believe the answer is:
nascent
'developing' is the definition.
(nascent means developing or just beginning)
'northern trip up a mountain?' is the wordplay.
'northern' becomes 'n' (abbreviation e.g. N. Ireland).
'trip up a mountain?' becomes 'ascent' (I've seen this in another clue).
'n'+'ascent'='NASCENT'
(Other definitions for nascent that I've seen before include "Being born - scan net (anag)" , "Beginning to show signs of potential" , "being developed" , "Just beginning existence" , "in early stages" .)