Of the period before Easter (6)
I believe the answer is:
lenten
'of the period before easter' is the definition.
(I've seen this before)
This is all the clue.
(Other definitions for lenten that I've seen before include "Of the pre-Easter period" , "Appropriate to period before Easter" , "Pertaining to time of fast" , "Of the Christian penitential season" , "Referring to a fast time" .)