Relate it better, having one’s letters (8)
I believe the answer is:
literate
'letters' is the definition.
Although both the answer and definition are singular nouns, I can't see how one could define the other.
'relate it better having one's' is the wordplay.
'it' becomes ''t' (abbreviation. e.g. in 'tis).
'better' indicates anagramming the letters (with an improved letter-order).
'having' means one lot of letters goes inside another.
'one' becomes 'i' (Roman numeral).
'relate'+'t'='relatet'
'relatet' anagrammed gives 'lterate'.
'lterate' enclosing 'i' is 'LITERATE'.
Can you help me to learn more?
(Other definitions for literate that I've seen before include "Well versed in books" , "well expressed" , "version of 'speed of light'?" , "Scholarly" , "Erudite" .)