Keep secret from neurotic lass, if yelling (8)
I believe the answer is:
classify
'keep secret' is the definition.
'from neurotic lass if yelling' is the wordplay.
'from' indicates a hidden word.
'CLASSIFY' can be found hidden inside 'neurotic lass if yelling'.
(Other definitions for classify that I've seen before include "Arrange in divisions" , "Arrange in categories" , "Order" , "catalogue?" , "Arrange systematically by group (8)" .)