Seafood reduced by a shilling, now £1 (4)
I believe the answer is:
quid
'ps1' is the definition.
I can't tell whether this definition defines the answer.
'seafood reduced by a shilling' is the wordplay.
'seafood' becomes 'squid' (squid is a kind of seafood).
'reduced by' suggests deleting specific letters.
'a shilling' becomes 's' (abbreviation e.g. Lsd - pounds, shillings, pence).
'squid' with 's' removed is 'QUID'.
'now' acts as a link.
Can you help me to learn more?
(Other definitions for quid that I've seen before include "Nicker (old slang)" , "1 GBP - piece of chewing tobacco" , "Wad of chewing tobacco" , "One fifth of a fiver" , "Pound (colloq.)" .)