It's worth having prayer: it's more unusual (10,4)
I believe the answer is:
collectors item
'it's worth' is the definition.
I can't tell whether this definition defines the answer.
'prayer it's more unusual' is the wordplay.
'prayer' becomes 'collect' (collect is a type of prayer).
'unusual' indicates anagramming the letters.
'its'+'more'='itsmore'
'itsmore' anagrammed gives 'orsitem'.
'collect'+'orsitem'='COLLECTORS ITEM'
'having' acts as a link.
Can you help me to learn more?
(Other definitions for collectors item that I've seen before include "much sought-after object" , "rarity" , "something rather special" , "Object that's precious" .)