The endless growth in snooker? (6)
I believe the answer is:
thwart
'snooker?' is the definition.
(I've seen this before)
'the endless growth' is the wordplay.
'endless' means to remove the last letter.
'growth' becomes 'wart' (I've seen this before).
'the' with its last letter taken off is 'th'.
'th'+'wart'='THWART'
'in' is the link.
(Other definitions for thwart that I've seen before include "Prevent from succeeding" , "Frustrate, prevent from doing" , "Frustrate and obstruct" , "Snooker" , "seat for oarsman" .)