Sundials and grandfather clocks perhaps (3-6)
I believe the answer is:
old-timers
'sundials' is the definition.
(I've seen this before)
'grandfather clocks perhaps' is the wordplay.
'grandfather' becomes 'old timer' (I have seen 'American grandfather' mean 'old timer' so perhaps 'grandfather' could also mean 'old timer').
'clocks perhaps' becomes 's' (I can't justify this - if you can you should give a lot more credence to this answer).
'oldtimer'+'s'='OLD-TIMERS'
'and' acts as a link.
Can you help me to learn more?
(Another definition for old-timers that I've seen is " People with long experience, like ancient watches".)