Job centre has opening, internally (5)
I believe the answer is:
chore
'job' is the definition.
('chore' can be a synonym of 'job')
'centre has opening internally' is the wordplay.
'centre' becomes 'core' (core is a kind of centre).
'opening' indicates taking the first letters.
'internally' indicates putting letters inside.
The initial letter of 'has' is 'h'.
'core' enclosing 'h' is 'CHORE'.
(Other definitions for chore that I've seen before include "Tedious routine task" , "Drudgery" , "Unpleasant task" , "Mundane task" , "Boring task" .)