Particular person following our team, Mark (7)
I believe the answer is:
fusspot
'particular person' is the definition.
(person who is fussy or particular)
'following our team mark' is the wordplay.
'following' becomes 'f' (used when citing page numbers etc).
'our team' becomes 'us' (the team with both of us).
'mark' becomes 'spot' (spotting is a kind of marking).
'f'+'us'+'spot'='FUSSPOT'
(Other definitions for fusspot that I've seen before include "Person hard to please" , "Hard-to-please person" , "Nervously agitating type" , "Finicky person" , "One who worries too much" .)