New slope developing (7)
I believe the answer is:
nascent
'developing' is the definition.
(nascent means developing or just beginning)
'new slope' is the wordplay.
'new' becomes 'n' (common abbreviation eg NT for New Testament).
'slope' becomes 'ascent' (ascent is a kind of slope).
'n'+'ascent'='NASCENT'
(Other definitions for nascent that I've seen before include "Developing" , "Beginning to show signs of potential" , "just coming into effect" , "Beginning to develop, embryonic" , "Budding early" .)