Wild, irrational fear at the rail terminus (5)
I believe the answer is:
feral
'wild' is the definition.
(similar in meaning)
'irrational fear at the rail terminus' is the wordplay.
'irrational' is an anagram indicator.
'at' says to put letters next to each other.
'the rail terminus' becomes 'l' (I can't explain this - if you can you should give a lot more credence to this answer).
'fear' with letters rearranged gives 'fera'.
'fera'+'l'='FERAL'
Can you help me to learn more?
(Other definitions for feral that I've seen before include "Wild or brutal" , "Flare up, going wild" , "Flare up in wild state" , "Flare up, being fierce" , "(Of an animal) running wild" .)