Allow to block path to goal in ball game (8)
I believe the answer is:
roulette
'ball game' is the definition.
(I've seen this in another clue)
'allow to block path' is the wordplay.
'allow to' becomes 'let' (I've seen this in another clue).
'block' means one lot of letters goes inside another (upper walls off glass inside formal).
'path' becomes 'route' (synonyms).
'let' inserted inside 'route' is 'ROULETTE'.
'to goal in' acts as a link.
This may not be correct. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for roulette that I've seen before include "Spinning-wheel game" , "sort of gambling" , "Whirling numbered wheel" , "Wheel for the gambler" , "Form of gambling" .)