Each letter is liberal (10)
I believe the answer is:
permissive
'liberal' is the definition.
(I've seen this before)
'each letter' is the wordplay.
'each' becomes 'per'.
'letter' becomes 'missive' (synonyms).
'per'+'missive'='PERMISSIVE'
'is' is the link.
(Other definitions for permissive that I've seen before include "granting authorisation" , "Liberal, broad-minded" , "Lenient, indulgent" , "Free" , "Showing indulgence" .)