Cleverly leading a seaman to a silly conclusion (4)
I believe the answer is:
ably
'cleverly' is the definition.
(thesaurus)
'leading a seaman to a silly conclusion' is the wordplay.
'leading' is a charade indicator (letters next to each other).
'a seaman' becomes 'ab' (short for able seaman).
'to a silly conclusion' becomes 'ly' (I can't explain this - if you can you should believe this answer much more).
'ab'+'ly' is 'ABLY'.
Can you help me to learn more?
(Other definitions for ably that I've seen before include "With competence" , "In a competent fashion" , "well" , "In proficient manner" , "With great skill" .)