Is felt mistakenly to suppress (6)
I believe the answer is:
stifle
'suppress' is the definition.
(stifling is a kind of suppressing)
'is felt mistakenly' is the wordplay.
'mistakenly' indicates anagramming the letters.
'is'+'felt'='isfelt'
'isfelt' with letters rearranged gives 'STIFLE'.
'to' acts as a link.
(Other definitions for stifle that I've seen before include "Asphyxiate - itself (anag)" , "Gag" , "Repress, choke" , "Suppress or suffocate" , "Quash" .)