Isolated rock from Route 51 (7)
I believe the answer is:
outlier
'isolated rock' is the definition.
(in geology, a rock isolated from others)
'route 51' is the wordplay.
I cannot really see how this works, but
'51' could be 'li' (Roman numerals) and 'li' is located in the answer.
an anagram of 'route' is 'outer' which is present in the left over letters.
This accounts for all the letters.
This may be the basis of the clue (or it may be nonsense).
'from' is the link.
Can you help me to learn more?
(Other definitions for outlier that I've seen before include "Something detached from the main grouping" , "One detached from main grouping" , "Anomalous data point" , "Extreme deviation from the mean - our tile (anag)" , "Isolated data point" .)