And hence puzzle was improved (8)
I believe the answer is:
enhanced
'improved' is the definition.
(enhancing is a kind of improving)
'and hence puzzle' is the wordplay.
'puzzle' indicates an anagram.
'and'+'hence'='andhence'
'andhence' with letters rearranged gives 'ENHANCED'.
'was' acts as a link.
(Other definitions for enhanced that I've seen before include "Improved in quality" , "Increased number" , "Extended" , "And hence? (anag)" , "Increased in value or quality" .)