Prepared lean crab and another crustacean (8)
I believe the answer is:
barnacle
'crustacean' is the definition.
(I know that Barnacle is a type of crustacean)
'prepared lean crab' is the wordplay.
'prepared' indicates anagramming the letters.
'lean'+'crab'='leancrab'
'leancrab' with letters rearranged gives 'BARNACLE'.
'and another' is the link.
(Other definitions for barnacle that I've seen before include "Marine crustacean (attaching to rocks, ships etc.)" , "hanger-on" , "One reluctant to leave" , "On the coast it's hard to remove" , "'Marine crustacean, attaches to a boat-hull (8)'" .)