Ruined page in ripped back of tattered dictionary (9)
I believe the answer is:
torpedoed
'ruined' is the definition.
(I've seen this before)
'page in ripped back of tattered dictionary' is the wordplay.
'page' becomes 'p'.
'in' indicates putting letters inside.
'ripped' becomes 'tore' (I've seen this before**).
'back of' suggests the final letters.
'dictionary' becomes 'oed' (Oxford English Dictionary).
The final letter of 'tattered' is 'd'.
'p' put into 'tore' is 'torpe'.
'torpe'+'d'+'oed'='TORPEDOED'
(Another definition for torpedoed that I've seen is " ruined".)