Open a delicacy reviewed in reference work (13)
I believe the answer is:
encyclopaedia
'reference work' is the definition.
(encyclopaedia is a kind of reference work)
'open a delicacy reviewed' is the wordplay.
'reviewed' indicates an anagram (letters reviewed or revised).
'open'+'a'+'delicacy'='openadelicacy'
'openadelicacy' is an anagram of 'ENCYCLOPAEDIA'.
'in' is the link.
(Other definitions for encyclopaedia that I've seen before include "Reference book on branches of knowledge" , "Large book of general knowledge" , "Book covering whole range of knowledge" , "Large reference book" , "Large reference work" .)