Number one went first without kit on (6)
I believe the answer is:
peeled
'number one' is the definition.
Both the definition and answer are adjectives. Perhaps you can see an association between them that I don't see?
'went first without kit on' is the wordplay.
'went first' becomes 'led' (I've seen this in another clue).
'without kit' becomes 'pee' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'on' means one lot of letters go next to another.
'led' put after 'pee' is 'PEELED'.
Can you help me to learn more?
(Other definitions for peeled that I've seen before include "Of fruit, skinned" , "Stripped the rind" , "Stripped the skin off" , "Took the skin off" , "Removed skin as from potato" .)