Writer first to fit in twin koala on vacation (5)
I believe the answer is:
kafka
'writer' is the definition.
(Kafka is an example)
'first to fit in twin koala on vacation' is the wordplay.
'first to' says to take the initial letters.
'in' indicates putting letters inside.
'twin' says to double the letters.
'on vacation' says to hollow out the word (remove centre letters).
'koala' with its centre taken out is 'ka'.
The first letter of 'fit' is 'f'.
'ka' duplicated is 'kaka'.
'f' put within 'kaka' is 'KAFKA'.
(Other definitions for kafka that I've seen before include "Novelist's" , "Franz ....., Czech author of 'The Trial'" , "Former Czech novelist" , "Franz -, Czech novelist (The Castle)" , "Franz ___ , Czech novelist, d. 1924" .)