Ireland releases information after hoarder makes plea for mercy (8)
I believe the answer is:
miserere
'plea for mercy' is the definition.
(I've seen this before)
'ireland releases information after hoarder' is the wordplay.
'ireland' becomes 'eire' (poetic name for Ireland).
'releases' suggests deleting specific letters.
'information' becomes 'i' (common abbreviation for information).
'after' means one lot of letters go next to another.
'hoarder' becomes 'miser' (I've seen this in another clue).
'eire' with 'i' taken out is 'ere'.
'ere' put after 'miser' is 'MISERERE'.
'makes' is the link.
(Other definitions for miserere that I've seen before include "Setting of Psalm fifty one" , "Mercy Seat" , "appeal for mercy" , "Psalm seeking mercy" , "plea for mercy" .)