Italian lake claims British musicians (5)
I believe the answer is:
combo
'musicians' is the definition.
(I've seen this before)
'italian lake claims british' is the wordplay.
'italian lake' becomes 'como' (I've seen this in another clue).
'claims' indicates putting letters inside.
'british' becomes 'b' (abbreviation e.g. in 'BBC').
'como' going around 'b' is 'COMBO'.
(Other definitions for combo that I've seen before include "Music group" , "Small (jazz or rock) band" , "musicians" , "group of players" , "Small jazz group" .)