Like a table in the chemistry lab? (8)
I believe the answer is:
periodic
'like' is the definition.
Both the definition and answer are adjectives. Maybe you can see an association between them that I can't see?
'a table in the chemistry lab?' is the wordplay.
'a' becomes 'per' (eg 'one a day' means 'one per day').
'table in the chemistry lab?' becomes 'iodic' (I can't explain this - if you can you should give a lot more credence to this answer).
'per'+'iodic'='PERIODIC'
(Other definitions for periodic that I've seen before include "Happening at intervals" , "Occurring or appearing at intervals" , "Intermittent" , "every now and then" , "Occasional" .)