Modern train at London: second from King’s Cross (14)

'modern' is the definition.
(synonyms)

'train at london second from king's cross' is the wordplay.
I cannot really understand how this works, but
'at' could be 'on' (location) and 'on' is located in the answer.
'second' could be 'd' and 'd' is found within the answer.
an anagram of 'train' is 'ntrai' which is present in the left over letters.
'from' could be 'o' (I've seen this in other clues) and 'o' is found in the answer.
'cross' could be 't' (shape) and 't' is found in the answer.
This explanation may well be incorrect...