Allow entertaining rogue to serve up shellfish (6)
I believe the answer is:
limpet
'shellfish' is the definition.
(I know that limpet is a type of shellfish)
'allow entertaining rogue' is the wordplay.
'allow' becomes 'let' (synonyms).
'entertaining' is an insertion indicator (inviting in, as for dinner).
'rogue' becomes 'imp'.
'let' going around 'imp' is 'LIMPET'.
'to serve up' is the link.
I am not very happy about this link. Some or all of it may be part of another bit of the clue.
Can you help me to learn more?
(Other definitions for limpet that I've seen before include "he's not easily got rid of" , "Gastropod that sticks to rocks" , "Proverbially clingy mollusc" , "It clings to rock surfaces" , "Rockpool clinger?" .)