Loads of weekend lessons? Only some (7)
I believe the answer is:
endless
'loads' is the definition.
'of weekend lessons? only some' is the wordplay.
'only some' indicates the answer is hidden within the clue.
'ENDLESS' can be found hidden inside 'of weekend lessons'.
(Other definitions for endless that I've seen before include "'Eternal, without finish (7)'" , "'Eternal, perpetual (7)'" , "Eternal or interminable" , "Going on forever, lacking conclusion" , "Going on and on, interminable" .)