Indicator as to where to put your name to the letters? (8)
I believe the answer is:
signpost
'indicator' is the definition.
(I've seen this before)
'your name to the letters?' is the wordplay.
'your' becomes 'sig' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'name' becomes 'n' (common abbreviation e.g. on forms).
'to the letters?' becomes 'post' (letters in the mail or post).
'sig'+'n'+'post'='SIGNPOST'
'as to where to put' is the link.
I am not very happy about this link. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for signpost that I've seen before include "this will give you directions" , "Direction marker" , "Guide, indicator" , "Postings (anag.)" , "Direction indicator" .)