Uninteresting musicians, learner admitted (5)
I believe the answer is:
bland
'uninteresting' is the definition.
(I've seen this before)
'musicians learner admitted' is the wordplay.
'musicians' becomes 'band' (I've seen this before).
'learner' becomes 'l'.
'admitted' means one lot of letters goes inside another.
'band' enclosing 'l' is 'BLAND'.
(Other definitions for bland that I've seen before include "Insipid - uninteresting" , "Mild; dull" , "Insipid; lacklustre" , "Dull - tasteless" , "without distinctive characteristics" .)