What does the cryptic crossword clue "Practises and secures top spin (10)" mean?

The definition is "Practises". The wordplay uses an anagram. anagram of SECURES + TOP = PROSECUTES; definition: "Practises" The answer is PROSECUTES.

Practises and secures top spin (10)

Guardian Cryptic #24124 | 20 Across | 2007-07-09 flower