Determined objective to include relative (9)
I believe the answer is:
insistent
'determined' is the definition.
(insistent can mean determined or tenacious)
'objective to include relative' is the wordplay.
'objective' becomes 'intent' (I've seen this in another clue).
'to include' indicates putting letters inside.
'relative' becomes 'sis' (short for sister).
'intent' going around 'sis' is 'INSISTENT'.
(Other definitions for insistent that I've seen before include "Unrelenting" , "Determined" , "Compelling attention" , "Unwilling to take "no" for an answer" , "Demanding attention" .)