Trailblazer on expedition initially requiring external support? (7)
I believe the answer is:
pioneer
'trailblazer' is the definition.
(both can mean an innovator)
'requiring external support?' is the wordplay.
'requiring' becomes 'one' (I can't justify this - if you can you should believe this answer much more).
'external' is an insertion indicator (I've seen this in other clues).
'support?' becomes 'pier' (type of structure).
'one' put within 'pier' is 'PIONEER'.
'on expedition initially' 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 pioneer that I've seen before include "Launch" , "Colonist" , "Original developer" , "Groundbreaker" , "To take first step" .)