Exclude secretively deceitful drinker (6)

I believe the answer is:

barfly

I'm a little stuck... Click here to teach me more about this clue!

'drinker' is the definition.
(thesaurus)

'exclude secretively deceitful' is the wordplay.
'exclude' becomes 'bar' (synonyms).
'secretively deceitful' becomes 'fly' (I can't justify this - if you can you should believe this answer much more).
'bar'+'fly'='BARFLY'

Can you help me to learn more?

(Other definitions for barfly that I've seen before include "frequenter of pubs" , "pub regular" .)

I've seen this clue in The Independent.

Want a hint initially instead of a full solution? Install my app