Scout sat back taking in fast snooker player (6,7)
I believe the answer is:
talent spotter
'scout' is the definition.
(I've seen this before)
'sat back taking in fast snooker player' is the wordplay.
'back' is a reversal indicator.
'taking in' means one lot of letters goes inside another.
'fast' becomes 'lent' (Lent is a period of fasting in Christianity).
'snooker player' becomes 'potter' (pots balls).
'sat' reversed gives 'tas'.
'tas' going around 'lent' is 'talents'.
'talents'+'potter'='TALENT-SPOTTER'
(Other definitions for talent spotter that I've seen before include "Agent looking for the gifted" , "Show business scout" , "One looking for good new performers" .)