Like melodious chorus of Cambridge that is welcoming learner (9)
I believe the answer is:
cantabile
'like melodious chorus' is the definition.
(cantabile means sung smoothly)
'cambridge that is welcoming learner' is the wordplay.
'cambridge' becomes 'Cantab' (short for Cantabrigian, meaning from Cambridge).
'that is' becomes 'ie' (short for Latin 'id est', 'that is').
'welcoming' is an insertion indicator (in sense of 'inviting in').
'learner' becomes 'l' (as in a learner driver with L-plates on their car).
'ie' going around 'l' is 'ile'.
'cantab'+'ile'='CANTABILE'
'of' is the link.
(Other definitions for cantabile that I've seen before include "In a smooth singing style - balance it (anag)" , "Melodious, as in singing - balance it (anag)" , "Mellifluous" , "(Of music) in a smooth singing style" , "In a singing style (mus.)" .)