Fishy letter to a Shakespearian shrew (5)
I believe the answer is:
skate
'fishy' is the definition.
(type of fish)
'shakespearian shrew' is the wordplay.
'shakespearian' becomes 's' (this could be a standard abbreviation I've not previously seen).
'shrew' becomes 'kate' (Katherina or Kate in The Taming of the Shrew).
's'+'kate'='SKATE'
'letter to a' is the link.
This may not be right. Some or all of it may belong to another bit of the clue.
Can you help me to learn more?
(Other definitions for skate that I've seen before include "Runner" , "Large, edible rays" , "Complete, 19-less" , "Cartilaginous fish" , "Type of ray" .)