Taught to sound tense (4)
I believe the answer is:
taut
'tense' is the definition.
(similar in meaning)
'taught to sound' is the wordplay.
'to sound' indicates a 'sounds like' (homophone) clue.
'taught' is a homophone of 'TAUT'.
(Other definitions for taut that I've seen before include "Tense, stretched tight" , "On the slope" , "Without slack" , "Pulled or drawn tight" , "Fully stretched" .)