Fool entering shot with old artist (7)
I believe the answer is:
picasso
'artist' is the definition.
(Picasso is an example)
'fool entering shot with old' is the wordplay.
'fool' becomes 'ass' (both can mean a stupid person).
'entering' means one lot of letters goes inside another.
'shot' becomes 'pic' (I've seen this in another clue).
'with' means one lot of letters go next to another.
'old' becomes 'o' (common abbreviation eg in OE for Old English).
'pic'+'o'='pico'
'ass' put within 'pico' is 'PICASSO'.
(Other definitions for picasso that I've seen before include "famous artist" , "Pablo . . . . . . ., extraordinary 20th century artist" , "Pablo ,,,,,,,, great late Spanish artist" , "Spanish painter and sculptor" , "Spanish artist, 1881-1973" .)