What does the cryptic crossword clue "Number one in lifting 80% excess weight (4)" mean?

The definition is "Number one". The wordplay uses a reversal. FLES (reversal="FLES") = SELF; definition: "Number one" The answer is SELF.

Number one in lifting 80% excess weight (4)

Guardian Cryptic #28950 | 3 Down | 2022-12-26 flower