Involve the file at the centre back (6)
I believe the answer is:
entail
'involve the file' is the definition.
'entail' can be an answer for 'involve' (entail means to involve or require). I am unsure of the 'the file' bit.
'the centre back' is the wordplay.
'the centre' becomes 'en' (I can't explain this - if you can you should give a lot more credence to this answer).
'back' becomes 'tail' (tail is a kind of back).
'en'+'tail'='ENTAIL'
'at' is the link.
Can you help me to learn more?
(Other definitions for entail that I've seen before include "If willing, this settles" , "Involve (something) as an inevitable consequence" , "Invlove or necessitate" , "settle estates for the long term" , "outmoded fashion" .)