Does honestly understand (8)
I believe the answer is:
construe
'understand' is the definition.
(construing is a kind of understanding)
'does honestly' is the wordplay.
'does' becomes 'cons' (both can mean to commit fraud).
'honestly' becomes 'true' (can be an adverb as in 'speak true', 'ring true').
'cons'+'true'='CONSTRUE'
(Other definitions for construe that I've seen before include "Read - trounces (anag)" , "Understand" , "Counters so as to interpret or explain" , "Recounts in order to interpret or explain" , "Analyse language" .)