Upset by current novel about a saint (2,1,4)
I believe the answer is:
in a stew
'upset' is the definition.
(I've seen this in another clue)
'current novel about a saint' is the wordplay.
'current' becomes 'I' (symbol for electric current).
'novel' becomes 'new' (novel means new or fresh).
'about' is an insertion indicator.
'saint' becomes 'st' (abbreviation).
'a'+'st'='ast'
'new' placed around 'ast' is 'nastew'.
'i'+'nastew'='IN A STEW'
'by' acts as a link.
(Other definitions for in a stew that I've seen before include "In a state of great agitation - simmering in pot?" , "Very worried" .)