Being hunted, one imagines, breaks ranks (5)
I believe the answer is:
snark
'being hunted one imagines' is the definition.
I know nothing about this answer so I can't judge whether it can be defined by this definition.
'breaks ranks' is the wordplay.
'breaks' indicates anagramming the letters.
'ranks' with letters rearranged gives 'SNARK'.
Can you help me to learn more?
(Other definitions for snark that I've seen before include "One hunted by sailors" , "Animal hunted in verse" , "One famously hunted" , "Hunt creature (Carroll)" , "The hunting of the - (Lewis Carroll)" .)