Shooting stick's outside, supporter set up (5)
I believe the answer is:
skeet
'shooting' is the definition.
(US shooting sport)
'stick's outside supporter set up' is the wordplay.
'outside' means to remove the middle letters.
'supporter' becomes 'tee' (I've seen this in other clues**).
'set up' says the letters should be written backwards.
'stick' with its middle removed is 'sk'.
'tee' back-to-front is 'eet'.
'sk'+'eet'='SKEET'
(Other definitions for skeet that I've seen before include "Form of clay pigeon shooting" , "US version of a shooting sport involving clay pigeons" , "A form of clay-pigeon shooting" , "American clay pigeon shooting" .)