Flawed, being tense (9)
I believe the answer is:
imperfect
This clue is a double definition.
'flawed' is the first definition.
(similar in meaning)
'being tense' is the second definition.
(the imperfect tense is a grammatical tense)
(Other definitions for imperfect that I've seen before include "seconds" , "Deficient" , "being immature" , "Faulty; tense" , "Flawed, defective" .)