Heart-starter is not analogue, for a start (9)
I believe the answer is:
digitalis
'analogue for a start' is the definition.
I can't judge whether this defines the answer.
'heart-starter is' is the wordplay.
'heart-starter' becomes 'digital' (I am not sure about this - if you are sure you should believe this answer much more).
'digital'+'is'='DIGITALIS'
'not' is the link.
Can you help me to learn more?
(Other definitions for digitalis that I've seen before include "Drug derived from foxglove leaves" , "Drug from foxgloves" , "Cardiac stimulant prepared from 11" , "plant making this drug?" , "Heart drug prepared from foxglove leaves" .)