Learner entering just to show natural ability (5)
I believe the answer is:
flair
'natural ability' is the definition.
(flair is a kind of natural ability)
'learner entering just' is the wordplay.
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'entering' indicates putting letters inside.
'just' becomes 'fair' (just can mean fair in the sense of showing justice).
'l' inserted into 'fair' is 'FLAIR'.
'to show' acts as a link.
(Other definitions for flair that I've seen before include "Natural ability or elegance" , "Stylishness, originality" , "Stylish talent" , "Faculty" , "Elan; panache" .)