Fear god coming in in the morning (5)
I believe the answer is:
alarm
'fear' is the definition.
(alarm is a kind of fear)
'god coming in in the morning' is the wordplay.
'god' becomes 'lar' (protective household god in ancient Rome).
'coming in' is an insertion indicator.
'in the morning' becomes 'am' (AM on a clock).
'lar' inserted within 'am' is 'ALARM'.
(Other definitions for alarm that I've seen before include "Strike fear" , "uneasiness" , "Shock; danger signal" , "Panicky concern" , "Fright" .)