Like 'La Mer', including A sharp (6)
I believe the answer is:
brainy
'a sharp' is the definition.
(I've seen this in another clue)
'like la mer including' is the wordplay.
I cannot really see how this works, but
'like' could be 'y' (similar in meaning) and 'y' is found within the answer.
The remaining letters 'brain' is a valid word which might be clued in a way I don't see.
This explanation may well be incorrect...
Can you help me to learn more?
(Other definitions for brainy that I've seen before include "Intellectual" , "Clever, got lots of grey matter" , "Binary (anag.)" , "Having a high IQ" , "smart?" .)