Choosy lads spoilt in time at Rugby, say (10)
I believe the answer is:
schooldays
'time at rugby say' is the definition.
(Rugby is an English public school)
'choosy lads spoilt' is the wordplay.
'spoilt' indicates an anagram.
'choosy'+'lads'='choosylads'
'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?" .)