Golf supporter into orienteering (3)
I believe the answer is:
tee
'golf supporter' is the definition.
'into orienteering' is the wordplay.
'into' says the answer is hidden in the clue.
'TEE' is hidden in the letters of 'orienteering'.
(Other definitions for tee that I've seen before include "Golfer drives from it" , "Start of a hole in golf" , "supporter on course" , "Golfer's peg" , "Peg for golfer" .)