Strong and independent -- a learner's promise (9)
I believe the answer is:
potential
'promise' is the definition.
(I've seen this before)
'strong and independent a learner's' is the wordplay.
'strong' becomes 'potent' (similar in meaning).
'and' says to put letters next to each other.
'independent' becomes 'i'.
'learner' becomes 'l'.
'potent'+'i'+'a'+'l'='POTENTIAL'
(Other definitions for potential that I've seen before include "Inherent, though latent, capacity" , "Powerful" , "Inherent capacity not realised" , "Latent, not yet actual" , "Possible (capacities of a person or situation)" .)