They try to score total: it's divided by a hundred (7)
I believe the answer is:
addicts
'they try to score' is the definition.
'total it's divided by a hundred' is the wordplay.
'total' becomes 'add' (synonyms).
'divided by' is an insertion indicator.
'a hundred' becomes 'C' (Roman numeral).
'its' going around 'c' is 'icts'.
'add'+'icts'='ADDICTS'
(Other definitions for addicts that I've seen before include "Habitual drug users" , "People who are hooked" , "People with compulsive ailments as for drugs" , "Junkies" .)