This person's with footballer, one eliminating danger in the main (11)
I believe the answer is:
minesweeper
'one eliminating danger in the main' is the definition.
Although both the answer and definition are singular nouns, I can't see how they can define each other.
'this person's with footballer' is the wordplay.
'this person's' becomes 'mine' (belonging to the person speaking or writing).
'with' is a charade indicator (letters next to each other).
'footballer' becomes 'sweeper' (I've seen this before).
'mine'+'sweeper'='MINESWEEPER'
Can you help me to learn more?
(Other definitions for minesweeper that I've seen before include "PC game" , "Warship" , "In the main, clearer" , "One removing bombs" , "Naval vessel" .)