How crabs move, and fish among rocks (8)
I believe the answer is:
sideways
'how crabs move' is the definition.
(crabs move sideways)
'fish among rocks' is the wordplay.
I cannot really understand how this works, but
'fish' could be 'ide' (I've seen this before) and 'ide' is found within the answer.
'rocks' could be 'sways' (I've seen this in another clue) and 'sways' is located in the leftover letters.
No letters remain.
This explanation may well be incorrect...
'and' is the link.
Can you help me to learn more?
(Other definitions for sideways that I've seen before include "Edgewise" , "Movement of crab" , "Obliquely" , "Askance" , "Not backwards or forwards" .)