Urge parent to order thrilling book (4-6)
I believe the answer is:
page-turner
'thrilling book' is the definition.
'urge parent to order' is the wordplay.
'to order' is an anagram indicator.
'urge'+'parent'='urgeparent'
'urgeparent' anagrammed gives 'PAGE-TURNER'.
(Other definitions for page-turner that I've seen before include "'Unputdownable' book" , "exciting book" , "Book one can't put down" , "Gripping book" .)