Period of fasting before Easter (4)
I believe the answer is:
'period of fasting before easter' is the definition.
(Christian fast leading up to Easter)
This is the entire clue.
(Other definitions for lent that I've seen before include "Gave for a limited period" , "Gave the use of for a time" , "Fast time" , "Loaned; a fast" , "From Ash Wednesday to Holy Saturday" .)