Focus of attention, medium in story easy to digest (9)
I believe the answer is:
limelight
'focus of attention' is the definition.
(I've seen this before)
'medium in story easy to digest' is the wordplay.
'medium' becomes 'm' (as in UK clothing sizes).
'in' is an insertion indicator.
'story' becomes 'lie' (story can mean a fabrication).
'easy to digest' becomes 'light' (as in a light meal).
'm' inserted into 'lie' is 'lime'.
'lime'+'light'='LIMELIGHT'
(Other definitions for limelight that I've seen before include "having prominence on stage" , "Intense publicity like stage illumination" , "Chaplin 1952 film" , "Media attention" , "A theatrical glower" .)