Peel initially rejected Irish nationalist demands (4)
I believe the answer is:
rind
'peel' is the definition.
(I know that peel can be written as rind)
'initially rejected irish nationalist demands' is the wordplay.
'initially' suggests taking the first letters.
The initial letters of 'rejected irish nationalist demands' is 'RIND'.
(Other definitions for rind that I've seen before include "'Peel, bark (4)'" , "Tough outer layer" , "Outer skin of citrus fruit" , "Skin of bacon" , "Hard outer skin, of an orange say" .)