Cover for me in case of train crashing (7)
I believe the answer is:
raiment
'cover' is the definition.
(I know that cover is a more specific form of the action raiment)
'me in case of train crashing' is the wordplay.
'in case of' means one lot of letters goes inside another (letters are encased in others).
'crashing' is an anagram indicator.
'train' is an anagram of 'raint'.
'me' inserted within 'raint' is 'RAIMENT'.
'for' acts as a link.
(Other definitions for raiment that I've seen before include "Minaret (anag) - clothing" , "Wear" , "dress?" , "Clothing (archaic)" , "Fancy clothes seen on minaret" .)