Float past lawman (5)
I believe the answer is:
bobby
'lawman' is the definition.
(bobby is a kind of lawman)
'float past' is the wordplay.
'float' becomes 'bob' (bob is a kind of float).
'past' becomes 'by' (as in years gone by).
'bob'+'by'='BOBBY'
(Other definitions for bobby that I've seen before include "beat man" , "-- Moore; -- Charlton (footballers)" , "A -dazzler, a -soxer" , "- Moore, World Cup winning captain" , "Rob" .)