Anxious future perhaps (5)
I believe the answer is:
tense
I believe this clue is a double definition.
'anxious' is the first definition.
(I've seen this in another clue)
'future perhaps' is the second definition.
(future tense)
(Other definitions for tense that I've seen before include "Verb form indicating time" , "far from comfortable" , "contract" , "past possibly" , "Form of verb showing time" .)