Troubles that exist in the Civil Service (5)
I believe the answer is:
cares
'troubles' is the definition.
'exist in the civil service' is the wordplay.
'exist' becomes 'are' (I've seen this before).
'in' means one lot of letters goes inside another.
'the civil service' becomes 'cs'.
'are' put into 'cs' is 'CARES'.
'that' is the link.
(Other definitions for cares that I've seen before include "Minds" , "Worries, anxieties" , "Has concerns or interest" , "Feels interest or concern" .)