Learner to flap around and grumble (5)
I believe the answer is:
bleat
'grumble' is the definition.
(both can mean to complain)
'learner to flap around' is the wordplay.
'learner' becomes 'l'.
'to flap' becomes 'beat' ('beat' can be a synonym of 'flap').
'around' indicates putting letters inside.
'l' inserted inside 'beat' is 'BLEAT'.
'and' acts as a link.
(Other definitions for bleat that I've seen before include "Sound from the fold" , "carp" , "Make a noise like a sheep" , "Make complaint" , "Lamb's cry" .)