Revealing Latvian spirit stocked by pub (7,2)
I believe the answer is:
letting on
'revealing' is the definition.
('let on' can be a synonym of 'reveal')
'latvian spirit stocked by pub' is the wordplay.
'latvian' becomes 'Lett' (I've seen this in another clue).
'spirit' becomes 'go'.
'stocked by' is an insertion indicator.
'pub' becomes 'inn' (an inn is a type of pub).
'go' going within 'inn' is 'ingon'.
'lett'+'ingon'='LETTING ON'
(Other definitions for letting on that I've seen before include "Giving information" , "feasibility of lease?" , "Revealing a secret" .)