Painful bill — object, spending time (6)
I believe the answer is:
aching
'painful' is the definition.
(similar in meaning)
'bill object spending time' is the wordplay.
'bill' becomes 'ac' (short for account).
'object' becomes 'thing' (an object is a thing or item).
'spending' indicates named letters should be taken away (to spend can mean to give out or give away).
'time' becomes 't' (abbreviation).
'thing' with 't' taken out is 'hing'.
'ac'+'hing'='ACHING'
(Other definitions for aching that I've seen before include "Suffering a dull persistent pain" , "Continuously sensitive" , "Giving continuous pain" , "Sore" , "Feeling pain" .)