Mostly better to keep hostilities away from the centre (7)
I believe the answer is:
outward
'from the centre' is the definition.
(moving from the centre)
'mostly better to keep hostilities away' is the wordplay.
'mostly' means to remove the last letter (most but not all of the word).
'better' becomes 'outdo' (to outdo is to beat or do better than).
'to keep' indicates putting letters inside.
'hostilities away' becomes 'war' (I can't explain this - if you can you should believe this answer much more).
'outdo' with its final letter taken away is 'outd'.
'outd' enclosing 'war' is 'OUTWARD'.
Can you help me to learn more?
(Other definitions for outward that I've seen before include "Apparent" , "Towards the exterior" , "Young person thus bound" , "(In the direction of the) exterior" , "External; superficial" .)