Shy personnel pull boxes (5)
I believe the answer is:
'shy' is the definition.
'personnel pull boxes' is the wordplay.
'personnel' becomes 'hr' (Human Resources).
'pull' becomes 'tow' (tow is a kind of pull).
'boxes' means one lot of letters goes inside another (the outside letters must 'box' inside letters in).
'hr' put inside 'tow' is 'THROW'.
(Other definitions for throw that I've seen before include "Light cloth cover for furniture" , "blanket" , "Propel through the air" , "Cast, lob" , "put on floor" .)