A rocking horse on dry land (6)
I believe the answer is:
ashore
'on dry land' is the definition.
(I've seen this before)
'a rocking horse' is the wordplay.
'rocking' indicates anagramming the letters.
'horse' is an anagram of 'shore'.
'a'+'shore'='ASHORE'
(Other definitions for ashore that I've seen before include "Returned to land" , "On land (as opposed to the sea)" , "beach" , "Home for the sailor" , "Off the boat" .)