Matt fixed puncture (4)
I believe the answer is:
flat
I believe this is a triple definition!
'matt' is the first definition.
(I know that matt can be written as flat)
'fixed' is the second definition.
(synonyms)
'puncture' is the third definition.
(I've seen this before)
(Other definitions for flat that I've seen before include "In music, below the correct pitch" , "Lacking interest" , "Dull; apartment" , "Horizontal" , "No longer charged" .)