Called for work to block river Dee (7)
I believe the answer is:
exacted
'called for' is the definition.
(exacting is a kind of calling for)
'work to block river dee' is the wordplay.
'work' becomes 'act' (synonyms).
'to block' is an insertion indicator (block can mean to fill a hole in something).
'river' becomes 'exe' (River Exe).
'dee' becomes 'd'.
'act' put inside 'exe' is 'exacte'.
'exacte'+'d'='EXACTED'
(Other definitions for exacted that I've seen before include "Obtained by force" , "Insisted on and obtained, say payment" , "Insisted on and obtained - in precise way?" , "Inflicted" , "forced out" .)