There's nothing in train to organise a share for you (6)
I believe the answer is:
ration
'a share for you' is the definition.
I can't judge whether this defines the answer.
'there's nothing in train to organise' is the wordplay.
'there's nothing' becomes 'o' (I've seen this in other clues).
'in' indicates putting letters inside.
'to organise' indicates anagramming the letters (I've seen 'organised' mean this).
'train' anagrammed gives 'ratin'.
'o' inserted into 'ratin' is 'RATION'.
Can you help me to learn more?
(Other definitions for ration that I've seen before include "Limit issue" , "Fixed share" , "Limit supply of (eg, food)" , "A measured portion in times of scarcity" , "Eke out" .)