Able to read a letter I rewrote (8)
I believe the answer is:
literate
'able to read' is the definition.
(I've seen this before)
'a letter i rewrote' is the wordplay.
'rewrote' is an anagram indicator (I've seen 'rewritten' mean this).
'a'+'letter'+'i'='aletteri'
'aletteri' is an anagram of 'LITERATE'.
(Other definitions for literate that I've seen before include "Relate it, being well read" , "Well versed in books" , "Learned" , "Erudite" , "properly educated" .)