Pulse right to coat in warm batter (9)
I believe the answer is:
heartbeat
'pulse' is the definition.
(I know that pulse can be written as heartbeat)
'right to coat in warm batter' is the wordplay.
'right' becomes 'r' (common abbreviation).
'to coat in' is an insertion indicator.
'warm' becomes 'heat'.
'batter' becomes 'beat'.
'r' placed inside 'heat' is 'heart'.
'heart'+'beat'='HEARTBEAT'
(Other definitions for heartbeat that I've seen before include "Animating force" , "Essential pulsation" , "Pulse of cardiac origin" , "Circulation noise" .)