Shake, shiver (7)
I believe the answer is:
tremble
I believe this clue is a double definition.
'shake' is the first definition.
(trembling is a kind of shaking)
'shiver' is the second definition.
(synonyms)
(Other definitions for tremble that I've seen before include "Look nervous" , "Quake in one's shoes" , "Betray nerves" , "get the shakes" , "sign of nerves" .)