Polyester centre? That's right (3)
I believe the answer is:
yes
'right' is the definition.
(right can mean yes or okay)
'polyester centre?' is the wordplay.
'centre?' says the answer is hidden in the clue (hidden in the middle of the letters).
'YES' can be found hidden inside 'polyester'.
'that's' acts as a link.
(Other definitions for yes that I've seen before include "Oui" , "Absolutely" , "Aye" , "One response to "will you marry me?"" , "Affirmative reply" .)