Obliged to jump to support job (4-5)
I believe the answer is:
duty-bound
'obliged' is the definition.
(I know that obliged can be written as duty-bound)
'jump to support job' is the wordplay.
'jump' becomes 'bound' (bounding is a kind of jumping).
'to support' means one lot of letters go next to another (in a down clue, some letters hold others up).
'job' becomes 'duty'.
'bound' put after 'duty' is 'DUTY-BOUND'.
'to' acts as a link.
(Other definitions for duty-bound that I've seen before include "Morally or legally obliged (to do something)" , "Under an obligation to do something" .)