What does the cryptic crossword clue "Stupidly set bulb that's prickly (7)" mean?

The definition is "prickly". The wordplay uses an anagram. anagram of SET + BULB = STUBBLE; definition: "prickly" The answer is STUBBLE.

Stupidly set bulb that's prickly (7)

Guardian Cryptic #24485 | 4 Down | 2008-09-04 flower