Silly old man at end of track? (6)
I believe the answer is:
buffer
I believe this is a double definition.
'silly old man' is the first definition.
(I've seen this before)
'at end of track?' is the second definition.
(a buffer is a piston at the end of a train track)
(Other definitions for buffer that I've seen before include "Protector against shock" , "doddery old man" , "Protect against shock" , "It lessons the force of an impact, something in between" , "sort of state" .)