Cleaner ticks off mourner (6-7)
I believe the answer is:
carpet-sweeper
'cleaner' is the definition.
(I've seen this before)
'ticks off mourner' is the wordplay.
'ticks off' becomes 'carpets' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'mourner' becomes 'weeper' (weeper is a kind of mourner).
'carpets'+'weeper'='CARPET-SWEEPER'
Can you help me to learn more?
(Other definitions for carpet-sweeper that I've seen before include "Domestic appliance for picking up dust" , "Cleaner" .)