Alleged Charlie was first to catch train (7)
I believe the answer is:
claimed
'alleged' is the definition.
(I've seen this in another clue)
'charlie was first to catch train' is the wordplay.
'charlie' becomes 'C' (phonetic alphabet: alpha, bravo, charlie etc.).
'was first' becomes 'led' (to lead is to go first).
'to catch' means one lot of letters goes inside another.
'train' becomes 'aim' (synonyms).
'led' going around 'aim' is 'laimed'.
'c'+'laimed'='CLAIMED'
(Other definitions for claimed that I've seen before include "Asserted right to or interest in" , "Declared" , "Asserted one's right to" , "Asserted, contended" , "Alleged" .)