Explorer one given all-round support (7)

I believe the answer is:

pioneer

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'explorer' is the definition.
(I've seen this before)

I cannot understand how the rest of the clue works.

(Other definitions for pioneer that I've seen before include "Original developer" , "Founder" , "Launch" , "First to explore a new area" , "person arriving early" .)

I've seen this clue in The Sun.

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