Present, past or future perfect (5)
I believe the answer is:
tense
I believe this clue is a double definition.
'present' is the first definition.
(present tense)
'past or future perfect' is the second definition.
(I know that past tense is a tense)
(Other definitions for tense that I've seen before include "In a nervous state" , "under stress?" , "Rigid, or grammatical time" , "edgy" , "Uneasy" .)