Give tuition to the retinue (5)
I believe the answer is:
train
'retinue' is the definition.
(both can mean people following an important person)
'give tuition to the' is the wordplay.
'give tuition' becomes 'rain' (I can't explain this - if you can you should give a lot more credence to this answer).
'to' is a charade indicator (letters next to each other) (I've seen this in other clues).
'the' becomes 't' (the is pronounced as a 't' sound in some dialects).
'rain' put after 't' is 'TRAIN'.
Can you help me to learn more?
(Other definitions for train that I've seen before include "Public transport on the railway" , "union's lengthy item" , "Help (someone) to become fit" , "Teach; followers" , "Succession of carriages" .)