Notice disagreement is rootless (6)
I believe the answer is:
adrift
'rootless' is the definition.
Both the definition and answer are adjectives. Perhaps they are linked in a way I don't understand?
'notice disagreement' is the wordplay.
'notice' becomes 'ad' (both can mean an advertisement).
'disagreement' becomes 'rift' (I've seen this in other clues).
'ad'+'rift'='ADRIFT'
'is' acts as a link.
Can you help me to learn more?
(Other definitions for adrift that I've seen before include "Loose from moorings" , "Afloat without steerage" , "out of touch" , "'Floating without direction, not tied up (6)'" , "without guidance?" .)