Additions in lines on cricket grounds (9)
I believe the answer is:
increases
'additions' is the definition.
(I know this)
'lines on cricket grounds' is the wordplay.
'lines' becomes 'creases' ('crease' can be a synonym of 'line').
'on' says to put letters next to each other.
'cricket grounds' becomes 'in' (I can't justify this - if you can you should give a lot more credence to this answer).
'creases' after 'in' is 'INCREASES'.
'in' is the link.
Can you help me to learn more?
(Other definitions for increases that I've seen before include "Becomes bigger" , "Becomes greater" , "Gets bigger" .)