Upset tin full of fish (6)
I believe the answer is:
shaken
'upset' is the definition.
(I've seen this in another clue)
'tin full of fish' is the wordplay.
'tin' becomes 'Sn' (Sn is the chemical symbol for tin).
'full of' indicates putting letters inside.
'fish' becomes 'hake' (hake is a kind of fish).
'sn' placed around 'hake' is 'SHAKEN'.
(Other definitions for shaken that I've seen before include "Jolted and shocked - like James Bond's martini?" , "Upset - rattled" , "Shocked or agitated" , "Shocked; astonished" , "Flourished" .)