Absent-minded cast, tense following Ursula's opening line (9)
I believe the answer is:
forgetful
'absent-minded' is the definition.
(I've seen this in another clue)
'cast tense following ursula's opening line' is the wordplay.
'cast' becomes 'forge' (as in casting or forging from metal).
'opening' says to take the initial letters.
'line' becomes 'l' (used when specifying particular lines from a poem).
The first letters of 'tense following ursulas' is 'tfu'.
'forge'+'tfu'+'l'='FORGETFUL'
(Other definitions for forgetful that I've seen before include "struggling to learn lines?" , "Absent-minded" , "Distracted" , "Inclined not to remember" , "Apt not to remember" .)