Doomed, but isn't upset during action (8)
I believe the answer is:
destined
'doomed' is the definition.
(I've seen this before)
'isn't upset during action' is the wordplay.
'upset' is an anagram indicator.
'during' indicates putting letters inside.
'action' becomes 'deed' (deed is a kind of action).
'isnt' with letters rearranged gives 'stin'.
'stin' inserted within 'deed' is 'DESTINED'.
'but' acts as a link.
(Other definitions for destined that I've seen before include "Intended; doomed" , "Didn't see, being fated" , "Fated, fore-ordained" , "Designated" , "Intended (for a particular end)" .)