Indicator by the way in initial letters? (8)
I believe the answer is:
signpost
'indicator' is the definition.
(I've seen this before)
'by the way in initial letters?' is the wordplay.
'by' is a charade indicator (letters next to each other).
'the way in initial' becomes 'sign' (I can't explain this - if you can you should give a lot more credence to this answer).
'letters?' becomes 'post' (letters in the mail or post).
'sign' next to 'post' is 'SIGNPOST'.
Can you help me to learn more?
(Other definitions for signpost that I've seen before include "Direction indicator" , "Wayside indicator" , "One may help you on your way" , "Postings (anag.)" , "Clue" .)