Is it the work of a month for the fisherman to catch it? (7)
I believe the answer is:
octopus
'a month for the fisherman to catch it?' is the definition.
I can't judge whether this defines the answer.
'is it the work' is the wordplay.
'is it' becomes 'oct' (I can't justify this - if you can you should believe this answer much more).
'the work' becomes 'opus' (an opus is an artistic work).
'oct'+'opus'='OCTOPUS'
'of' acts as a link.
Can you help me to learn more?
(Other definitions for octopus that I've seen before include "Scoot up (anag.)" , "Long-tentacled creature" , "Eight-limbed cephalopod" , "person with widespread influence" , "Creature with eight limbs" .)