For every writer, I'd curl a review at right angles (13)
I believe the answer is:
perpendicular
'at right angles' is the definition.
(I've seen this before)
'for every writer i'd curl a review' is the wordplay.
'for every' becomes 'per' ('per' means 'for each' or 'for every').
'writer' becomes 'pen' (something which writes).
'review' is an anagram indicator.
'id'+'curl'+'a'='idcurla'
'idcurla' with letters rearranged gives 'dicular'.
'per'+'pen'+'dicular'='PERPENDICULAR'
(Other definitions for perpendicular that I've seen before include "Vertical - at 90 degrees" , "Vertical; upright" , "At right angles" , "Like this answer [1A], relative to 1 dn" , "Sort of architecture" .)