Pass on support stone (9)
I believe the answer is:
propagate
'pass on' is the definition.
(propagating is a kind of passing on)
'support stone' is the wordplay.
'support' becomes 'prop' (prop up can mean to support).
'stone' becomes 'agate' (agate is a type of stone).
'prop'+'agate'='PROPAGATE'
(Other definitions for propagate that I've seen before include "Increase by natural process" , "Cause to reproduce" , "Grow (plants) or spread (ideas)" , "widely spread" , "Publicise" .)