Refusal and, ultimately, approval (3)
I believe the answer is:
nod
'approval' is the definition.
(thesaurus)
'refusal and ultimately' is the wordplay.
'refusal' becomes 'no'.
'ultimately' indicates one should take the final letters.
The last letter of 'and' is 'd'.
'no'+'d'='NOD'
(Other definitions for nod that I've seen before include "Go to sleep in this land" , "positive sign" , "may get gesture of approval" , "Gesture of acceptance" , "Assent with head movement (3)" .)