Lied badly about theologian's do (6)
I believe the answer is:
diddle
'do' is the definition.
(I've seen this before)
'lied badly about theologian's' is the wordplay.
'badly' indicates anagramming the letters.
'about' means one lot of letters goes inside another.
'theologian' becomes 'dd' (Doctor of Divinity degree).
'lied' is an anagram of 'dile'.
'dile' enclosing 'dd' is 'DIDDLE'.
(Other definitions for diddle that I've seen before include "Fleece" , "Con - do - lidded (anag)" , "Slangily cheat or swindle" , "Did, and led out to cheat" , "Slang for cheat or swindle - nearly fiddle" .)