Business costs when rising ultimately awful sign (8)
I believe the answer is:
salaries
'business costs' is the definition.
'salaries' can be an answer for 'costs' (salary is a kind of cost). I am not certain of the 'business' bit.
'when rising ultimately awful sign' is the wordplay.
'when' becomes 'as' (eg 'when I walked' means 'as I walked').
'rising' is a reversal indicator (letters written upwards in a down clue).
'ultimately' indicates one should take the final letters.
'sign' becomes 'aries' (star sign).
The last letter of 'awful' is 'l'.
'as' reversed gives 'sa'.
'sa'+'l'+'aries'='SALARIES'
Can you help me to learn more?
(Other definitions for salaries that I've seen before include "remuneration" , "Payments from employers" , "Wages" .)