Conscription not right — it's ridiculous (4)
I believe the answer is:
daft
'ridiculous' is the definition.
(thesaurus)
'conscription not right it's' is the wordplay.
'conscription' becomes 'draft' ('draft' can be a synonym of 'conscription').
'not' indicates named letters should be taken away.
'right' becomes 'rt'.
'it' becomes 't' (abbreviation. e.g. in 'tis).
'draft' with 'rt' removed is 'daf'.
'daf'+'t'='DAFT'
(Other definitions for daft that I've seen before include "'---- as a brush': dotty" , "Idiotic" , "Stupid" , "Informally silly or crazy" , "Barmy, crackers" .)