Observed in Marbella, this club (5)
I believe the answer is:
lathi
'club' is the definition.
(type of baton used in British India)
'observed in marbella this' is the wordplay.
'observed in' says the answer is hidden in the clue.
'LATHI' can be found hidden inside 'marbella this'.
(Other definitions for lathi that I've seen before include "Indian truncheon" , "Heavy iron-bound stick used for crowd control by police in India" , "Indian police baton" , "Indian policeman's stick" , "Long, heavy stick" .)