What does the cryptic crossword clue "When jiggled about, pin set to move! (4,2,2)" mean?

The definition is "move!". The wordplay uses an anagram. anagram of PIN + SET + TO = STEP ON IT; definition: "move!" The answer is Step on it.

When jiggled about, pin set to move! (4,2,2)

Telegraph Prize Cryptic #3036 | 1 Down | 2019-12-29 flower