Football club employing round ball is concentrating (8)
I believe the answer is:
focusing
'is concentrating' is the definition.
(I've seen this in another clue)
'football club employing round ball' is the wordplay.
'football club' becomes 'FC'.
'employing' becomes 'using' (to employ is to use).
'round' means one lot of letters goes inside another.
'ball' becomes 'o' (O looks like a ball).
'fc'+'using'='fcusing'
'fcusing' placed around 'o' is 'FOCUSING'.
(Other definitions for focusing that I've seen before include "Adjusting a camera lens" , "Moving the lens so as to get the sharpest image" , "meeting at one point" .)