So a learner is a little chap (3)
I believe the answer is:
sol
'chap' is the definition.
'so a learner is a little' is the wordplay.
'a learner' becomes 'l' (as in a learner driver with L-plates on their car).
'little' means to remove the last letter (the word is not quite complete).
'so'+'l'+'a'='sola'
'sola' with its final letter taken away is 'SOL'.
(Other definitions for sol that I've seen before include "Personification of the sun" , "Note - colloid - the Sun" , "Spanish and poetic sun" , "Roman sun-god" , "nearby star" .)