Marine predator had pass to pass around Greene novel (6,3)
I believe the answer is:
conger eel
'marine predator had pass' is the definition.
I can't tell whether this defines the answer.
'pass around greene novel' is the wordplay.
'pass' becomes 'col' (col is a term for a mountain pass).
'around' is an insertion indicator.
'novel' indicates anagramming the letters (letters in a new or novel order).
'greene' anagrammed gives 'ngeree'.
'col' going around 'ngeree' is 'CONGER-EEL'.
'to' is the link.
Can you help me to learn more?
(Other definitions for conger eel that I've seen before include "Large slippery fish" , "long haul?" , "swimmer" , "one is long in the water" , "Predatory sea creature" .)