False modesty mainly protects her, being stifled (9)
I believe the answer is:
smothered
'stifled' is the definition.
('smother' can be a synonym of 'stifle')
'false modesty mainly protects her' is the wordplay.
'false' indicates an anagram.
'mainly' means to remove the last letter.
'protects' is an insertion indicator.
'modesty' with its final letter taken off is 'modest'.
'modest' with letters rearranged gives 'smoted'.
'smoted' going around 'her' is 'SMOTHERED'.
'being' acts as a link.
(Other definitions for smothered that I've seen before include "Stifled" , "Suffocated" , "given too little air" , "cocooned?" , "Such a mate" .)