Follows lecture in case of sepsis (6)
I believe the answer is:
stalks
'follows' is the definition.
(stalk is a kind of follow)
'lecture in case of sepsis' is the wordplay.
'lecture' becomes 'talk' (synonyms).
'in' indicates putting letters inside.
'case of' suggests removing the centre (outsides of).
'sepsis' with its centre removed is 'ss'.
'talk' placed inside 'ss' is 'STALKS'.
(Other definitions for stalks that I've seen before include "Follows stealthily with evil intent" , "Pursues stealthily, game or person" , "They support plants" , "Tracks or pursues stealthily" , "Main stems of plants" .)