Last post up. The thing the writer has going for training (7)
I believe the answer is:
tuition
'for training' is the definition.
(I've seen this before)
'last post up the thing the writer has going' is the wordplay.
'last post up' becomes 'tu' (I can't explain this - if you can you should believe this answer much more).
'the thing' becomes 'it'.
'the writer' becomes 'I' (the person who is writing these clues).
'has' is a charade indicator (letters next to each other).
'going' becomes 'on' (both can mean functioning or activated).
'tu'+'it'+'i'+'on'='TUITION'
Can you help me to learn more?
(Other definitions for tuition that I've seen before include "Teaching, instruction" , "practice" , "Schooling" , "Personal coaching" , "(Individual) instruction" .)