Count without feeling fear occasionally (6)
I believe the answer is:
number
'count' is the definition.
(synonyms)
'without feeling fear occasionally' is the wordplay.
'without feeling' becomes 'numb' (numb means not feeling anything).
'occasionally' means one should take alternating letters (letters taken at regular intervals or occasions).
The alternate letters of 'fear' are 'er'.
'numb'+'er'='NUMBER'
(Other definitions for number that I've seen before include "One may be irrational or negative" , "Mathematical value" , "comparatively lacking in feeling" , "28 down, for instance" , "Digit, integer" .)