16 down
Initial
contribution
to
thread
that
gives
clear
directions
(8)
Initial contribution to thread that gives clear directions (8)
hints
0
checks
0
hints
The definition is at the end of the clue.
How the clue works
See that gives clear directions at the end — that's your definition, pointing to a signpost. For the wordplay, it's built in two bits: SIGN, as in initialling something, is stuck together with POST, the sort of contribution you'd make to a discussion thread, giving you the answer.