Woman unusually hot when stuffing fish (7)
I believe the answer is:
dorothy
'woman' is the definition.
'unusually hot when stuffing fish' is the wordplay.
'unusually' indicates anagramming the letters.
'when stuffing' is an insertion indicator (inserted letters are stuffed into others).
'fish' becomes 'dory' (dory is a kind of fish).
'hot' anagrammed gives 'oth'.
'oth' inserted into 'dory' is 'DOROTHY'.
(Other definitions for dorothy that I've seen before include "Female" , "Woman" , "one of 5d's troupe" , "Wizard of Oz child" , "Name of the young heroine in 'The Wizard of Oz'" .)