definition of
[pick at]

[1] #1 pick at v. pluck or pull at with the fingers; "She picked nervously at the buttons of her blouse". wn

[2] #2 pick at v. eat like a bird; "The anorexic girl just picks at her food". wn

[3] #3 pick at v. express a negative opinion of; "She disparaged her student's efforts". wn