Board train right away, please (9)
I believe the answer is:
entertain
'please' is the definition.
(I've seen this before)
'board train right away' is the wordplay.
'board' becomes 'enter' (I've seen this in another clue).
'right' becomes 'r' (common abbreviation).
'away' is a deletion indicator.
'train' with 'r' taken away is 'tain'.
'enter'+'tain'='ENTERTAIN'
(Other definitions for entertain that I've seen before include "Have a mind to - have a party" , "Amuse or take into consideration" , "cheer" , "Wine and dine" , "Please < flirt with" .)