Angry girl hiding in cover (5)
I believe the answer is:
livid
'angry' is the definition.
(I've seen this before)
'girl hiding in cover' is the wordplay.
'girl' becomes 'Vi' (short for Violet).
'hiding in' is an insertion indicator.
'cover' becomes 'lid' (lid is a kind of cover).
'vi' going into 'lid' is 'LIVID'.
(Other definitions for livid that I've seen before include "some more [old cardinals]" , "Furiously angry - leaden coloured?" , "Apoplectic" , "Furiously angry, the colour of lead" , "Enraged" .)