Easy clue oddly written by party for "coin" (6)
I believe the answer is:
escudo
'for coin' is the definition.
(I've seen this before)
'easy clue oddly written by party' is the wordplay.
'oddly' means one should take alternating letters (letters in the odd-numbered positions are used).
'written by' means one lot of letters go next to another.
'party' becomes 'do' (do can informally mean a party).
'easy'+'clue'='easyclue'
The alternating letters of 'easyclue' are 'escu'.
'escu'+'do'='ESCUDO'
(Other definitions for escudo that I've seen before include "Former Eur. currency" , "Old bit of Lisbon" , "Former currency of Portugal" , "Smash in C Verde" , "Former Portuguese monetary unit" .)