Up to the job (4)
I believe the answer is:
able
'up to the job' is the definition.
(I've seen this in another clue)
This is the entire clue.
(Other definitions for able that I've seen before include "Fit as a seaman" , "See 21" , "... was I ere I saw Elba (palindrome)" , "Competent and equipped" , "Efficient" .)