Cut off from central Ruislip at all times (5)
I believe the answer is:
sever
'cut off' is the definition.
(to sever is to cut)
'central ruislip at all times' is the wordplay.
'central' indicates the central letters.
'at all times' becomes 'ever' (synonyms).
The central letter of 'ruislip' is 's'.
's'+'ever'='SEVER'
'from' acts as a link.
(Other definitions for sever that I've seen before include "Disconnect" , "Cut apart, maybe a relationship" , "Cut off, separate" , "Cleave" , "Verse (anag)" .)