One staying behind in person? (12)
I believe the answer is:
wicketkeeper
'one staying behind' is the definition.
The definition suggests a singular noun which matches the answer.
'person?' is the wordplay.
I cannot really understand how this works, but
'person?' could be 'keeper' (keeper is a kind of person) and 'keeper' is found within the answer.
The remaining letters 'wicket' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
'in' acts as a link.
Can you help me to learn more?
(Other definitions for wicketkeeper that I've seen before include "Cricketer" , "Cricket player" , "Close fielder" , "Stumper" , "Fielder behind stumps" .)