Travelling collier, heading off round eastern rock (7)
I believe the answer is:
lorelei
'rock' is the definition.
(rock by the River Rhine in Germany)
'travelling collier heading off round eastern' is the wordplay.
'travelling' indicates an anagram.
'heading off' means to remove the first letter.
'round' means one lot of letters goes inside another.
'eastern' becomes 'e'.
'collier' with its initial letter removed is 'ollier'.
'ollier' with letters rearranged gives 'loreli'.
'loreli' going around 'e' is 'LORELEI'.
(Other definitions for lorelei that I've seen before include "Rhine rock famed for siren" , "voice to die for" , "Fateful singer" , "Rhine rock of siren legend" , "Great Rock on the Rhine where 37 across lived" .)