A large fish actor gives the producer of Campion (9)
I believe the answer is:
allingham
'the producer of campion' is the definition.
I don't know anything about this answer so I cannot judge whether this works.
'a large fish actor' is the wordplay.
'large' becomes 'L' (eg in clothes sizes).
'fish' becomes 'ling' (ling is a kind of fish).
'actor' becomes 'ham' (ham is a kind of actor).
'a'+'l'+'ling'+'ham'='ALLINGHAM'
'gives' is the link.
Can you help me to learn more?
(Other definitions for allingham that I've seen before include "She wrote detective stories" , "Margery --, author" , "Margery --, English crime writer" .)