Religious celebration fixed around 2nd February (5)
I believe the answer is:
feast
'religious celebration' is the definition.
(as in the feast day of a saint)
'fixed around 2nd february' is the wordplay.
'fixed' becomes 'fast' (synonyms).
'around' indicates putting letters inside.
'2nd february' becomes 'e' (2nd letter of 'february').
'fast' enclosing 'e' is 'FEAST'.
(Other definitions for feast that I've seen before include "Beano" , "Junket" , "entertainment" , "Extravagant meal" , "Grand meal" .)