Resident in Latvia grabs potent drug (6)
I believe the answer is:
viagra
'potent drug' is the definition.
(viagra is a kind of potent drug)
'resident in latvia grabs' is the wordplay.
'resident' says the answer is hidden in the clue (I've seen 'resident of' mean this).
'VIAGRA' is hidden within 'in latvia grabs'.
(Other definitions for viagra that I've seen before include "Male sexual aid" , "Sildenafil citrate" , "Controversial pills" , "Drug treating impotence" , "Drug aiding one's sex life" .)