This one does by not being in line? (7)
I believe the answer is:
disobey
'line?' is the definition.
Although both the answer and definition are verbs in their base form, I cannot see how they can define each other.
'this one does by not being' is the wordplay.
'this one does by' becomes 'dis' (I am not sure about this - if you are sure you should give a lot more credence to this answer).
'not' becomes 'o' (I've seen this in other clues).
'being' becomes 'bey' (bey is a kind of being).
'dis'+'o'+'bey'='DISOBEY'
'in' acts as a link.
(Other definitions for disobey that I've seen before include "Defy" , "Contravene" , "Refuse to comply" , "Refuse to take orders" , "Fail to carry out (order)" .)