Upset fish in tin (6)
I believe the answer is:
shaken
'upset' is the definition.
(I've seen this in another clue)
'fish in tin' is the wordplay.
'fish' becomes 'hake' (hake is a kind of fish).
'in' means one lot of letters goes inside another.
'tin' becomes 'Sn' (Sn is the chemical symbol for tin).
'hake' inserted into 'sn' is 'SHAKEN'.
(Other definitions for shaken that I've seen before include "Upset or agitated" , "Agitated or joggled" , "Shocked, unnerved" , "Shocked or agitated" , "James Bond liked his martinis this way, not stirred" .)