Reportedly, old red wines must be strained (5)
I believe the answer is:
tense
'be strained' is the definition.
(similar in meaning)
I don't understand how the rest of the clue works.
Can you help me to learn more?
(Other definitions for tense that I've seen before include "past possibly" , "Drawn" , "quite possibly perfect" , "Maybe future" , "perfect, perhaps" .)