Fish heads from lake offloaded at Caen harbour (5)
I believe the answer is:
loach
'fish' is the definition.
(I know that loach is a type of fish)
'heads from lake offloaded at caen harbour' is the wordplay.
I cannot really see how this works, but
'from' could be 'o' (I've seen this in other clues) and 'o' is present in the answer.
'lake' could be 'l' (geographical abbreviation) and 'l' is found within the answer.
The remaining letters 'ach' is a valid word which might be clued in a way I don't understand.
This may be the basis of the clue (or it may be nonsense).
Can you help me to learn more?
(Other definitions for loach that I've seen before include "Fish with barbels around mouth" , "Film-maker" , "Freshwater fish; rhymes with freshwater fish" , "River fish - film director" , "Fish - British film director" .)