Fish got nurse worried (8)
I believe the answer is:
sturgeon
'fish' is the definition.
(type of fish)
'got nurse worried' is the wordplay.
'worried' is an anagram indicator (worry can mean to interfere with or disturb).
'got'+'nurse'='gotnurse'
'gotnurse' with letters rearranged gives 'STURGEON'.
(Other definitions for sturgeon that I've seen before include "Source of caviar" , "Fish from which caviar is obtained" , "The fish for caviars" , "Fish yielding caviar and isinglass" , "swimmer" .)