Times sign has gone from outside for good (9)
I believe the answer is:
eternally
'for good' is the definition.
(I've seen this before)
'times sign has gone from outside' is the wordplay.
'times sign' becomes 'x' (x is the multiplication sign).
'has gone from' suggests deleting specific letters.
'outside' becomes 'externally' (I've seen this before).
'externally' with 'x' taken out is 'ETERNALLY'.
(Other definitions for eternally that I've seen before include "Always and forever" , "all the time" , "For evermore" , "for good" , "constantly" .)