On land presumably lad's quiet time (3,6)
I believe the answer is:
off season
'quiet time' is the definition.
'off season' can be an answer for 'time' (I have seen 'Slack time' mean 'off season' so perhaps 'time' could also mean 'off season'). I'm unsure of the 'quiet' bit.
'on land presumably lad's' is the wordplay.
'on' is a charade indicator (letters next to each other).
'land presumably' becomes 'offsea' (I can't explain this - if you can you should give a lot more credence to this answer).
'lad' becomes 'son' (lad can informally mean a young boy).
'offsea' put next to 'son' is 'OFF-SEASON'.
Can you help me to learn more?
(Other definitions for off season that I've seen before include "when costs are cheaper?" , "slack period" , "Time of year when business is slackest" , "In less busy time" , "Time of year when usual activity or business is slack" .)