Choosy lads spoilt in time at Rugby, say (10)
I believe the answer is:
'time at rugby say' is the definition.
(Rugby is an English public school)
'choosy lads spoilt' is the wordplay.
'spoilt' indicates an anagram.
'choosylads' with letters rearranged gives 'SCHOOLDAYS'.
'in' is the link.
(Other definitions for schooldays that I've seen before include "Choosy lads (anag) -- life's learning time?" , "Happiest days of your life?" .)