Line framed by Wessex writer? Scarcely! (6)
I believe the answer is:
hardly
'scarcely' is the definition.
(I know that scarcely can be written as hardly)
'line framed by wessex writer?' is the wordplay.
'line' becomes 'l' (used when specifying particular lines from a poem).
'framed by' is an insertion indicator.
'wessex writer?' becomes 'Hardy' (Thomas Hardy set novels in Wessex).
'l' going into 'hardy' is 'HARDLY'.
(Other definitions for hardly that I've seen before include "Almost not" , "With great difficulty" , "Not much" , "Not quite "It seems unlikely!"" , "Barely, scarcely" .)