Dad's fun paperback to take on holiday? (8)

I believe the answer is:
passport
'paperback to take on holiday?' is the definition.
I can't judge whether this defines the answer.
'dad's fun' is the wordplay.
'dad's' becomes 'pa's' (both can mean one's father).
'fun' becomes 'sport' (synonyms).
'pas'+'sport'='PASSPORT'
Can you help me to learn more?
(Other definitions for passport that I've seen before include "This ensures admission" , "Document facilitating travel" , "Traveller's ID" , "entry permit?" , "Traveller's aid" .)
