Given to them temporarily prior to Easter (4)
I believe the answer is:
lent
'easter' is the definition.
(thesaurus)
I can't explain the remainder of the clue.
Can you help me to learn more?
(Other definitions for lent that I've seen before include "Christian period of abstinence" , "Fast time" , "Christian penitential period" , "Forty days of penance" , "Gave the use of for a time" .)