Last letter in some dialect (5)
I believe the answer is:
final
'last' is the definition.
(I know that last can be written as final)
'letter in some dialect' is the wordplay.
'letter in' becomes 'fina' (I am not sure about this - if you are sure you should believe this answer much more).
'some' indicates the central letters.
The centre of 'dialect' is 'l'.
'fina'+'l'='FINAL'
Can you help me to learn more?
(Other definitions for final that I've seen before include "Concluding" , "Not to be altered" , "Conclusive" , "The last exam or leg of competition" , "Last in a series of games or contests" .)