Musical quality means a lot to a learner (5)
I believe the answer is:
tonal
'musical' is the definition.
(I've seen this in another clue)
'lot to a learner' is the wordplay.
'lot' becomes 'ton' (I've seen this in another clue).
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'ton'+'a'+'l'='TONAL'
'quality means a' is the link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for tonal that I've seen before include "Written in conventional keys and harmony" , "Like music that uses keys" , "According to musical key" , "With conventional key and harmony" , "Using conventional keys/harmonies" .)