Remained far from flippant, by the sound of it (6)
I believe the answer is:
stayed
'remained' is the definition.
(staying is a kind of remaining)
'far from flippant by the sound of it' is the wordplay.
'far from flippant' becomes 'staid' (I've seen this in another clue).
'by the sound of it' indicates a 'sounds like' (homophone) clue.
'staid' sounds like 'STAYED'.
(Other definitions for stayed that I've seen before include "Remained or deferred" , "Remained in the same place" , "Withheld; remained" , "Continued" , "having support" .)