It's often potted and propagated with top removed (3)
I believe the answer is:
red
'it's often potted' is the definition.
(red ball in billiards, snooker etc)
'propagated with top removed' is the wordplay.
'propagated' becomes 'bred' (I've seen this before).
'with top removed' means to remove the first letter.
'bred' with its initial letter taken away is 'RED'.
'and' acts as a link.
(Other definitions for red that I've seen before include "Blood-coloured" , "Merchant flag" , "Colour of garnets" , "socialist?" , "Glowing" .)