Rambler runs on top (5)
I believe the answer is:
rover
'rambler' is the definition.
(I've seen this before)
'runs on top' is the wordplay.
I cannot really understand how this works, but
'runs' could be 'r' (cricket abbreviation) and 'r' is present in the answer.
'on' could be 'over' (over can mean on top of) and 'over' is present in the answer.
No letters remain.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for rover that I've seen before include "rambler" , "Wanderer, traveller" , "A vagrant" , "Car - dog" , "Pirate; dog's name" .)