Ineffective and also extremely tough? Not as much (9)
I believe the answer is:
toothless
'ineffective' is the definition.
(I've seen this before)
'also extremely tough? not as much' is the wordplay.
'also' becomes 'too' ('too' can be a synonym of 'also').
'extremely' suggests removing the centre.
'not as much' becomes 'less' ('less' can be similar in meaning to 'not as much').
'tough' with its centre removed is 'th'.
'too'+'th'+'less'='TOOTHLESS'
'and' acts as a link.
(Other definitions for toothless that I've seen before include "Deprived of power" , "Lacking power" , "Lacking in force" , "Unable to chew; ineffective (sanction)" .)